RustyNES Development Roadmap

Document Version: 2.11.0 Last Updated: 2025-12-29 Project Status: Phase 1.5 Stabilization In Progress (M1-M8 Complete, M9 85%, M10 50%, M11 83%)

Overview
Development Phases
Phase 1: MVP (Months 1-6)
Phase 1.5: Stabilization & Accuracy (Months 7-9)
Phase 2: Advanced Features (Months 10-15)
Phase 3: Expansion (Months 13-18)
Phase 4: Polish & Release (Months 19-24)
Milestone Tracking
Feature Priorities
Testing Strategy

Recent Updates (v2.15.0 - December 2025)

v0.8.6 Released - December 29, 2025 - Sub-Cycle Accuracy Improvements (M11 S3-S5)!

M11 Sub-Cycle Accuracy Achievements (Sprints 3-5):

DMC DMA Cycle Stealing: Proper CPU stall handling during DMC sample fetches
NES Open Bus Behavior: last_bus_value tracking for hardware-accurate unmapped reads
Controller Open Bus: Bits 5-7 correctly mixed from open bus in controller reads
Per-Cycle Mapper Clocking: mapper.clock(1) in on_cpu_cycle() for IRQ accuracy
Test Suite: 522+ tests passing (0 failures, 1 ignored doctest, 2 new tests)
100% Blargg Pass Rate: All 90/90 Blargg tests continue to pass
M11 Progress: 5/6 sprints complete (83%)

v0.8.5 Released - December 29, 2025 - Cycle-Accurate CPU/PPU Synchronization!

M11 Sub-Cycle Accuracy Achievements (Sprints 1 & 2):

CpuBus Trait: New trait extends Bus with on_cpu_cycle() callback for PPU stepping
cpu.tick() Method: Cycle-by-cycle CPU execution for sub-instruction timing precision
VBlank Timing Tests: Now pass with ±0 cycle accuracy (ppu_02 was ±51, ppu_03 was ±10)
Test Harness: Updated to use CpuBus for cycle-accurate validation
Test Suite: 520+ tests passing (0 failures, 1 ignored doctest)
100% Blargg Pass Rate: All 90/90 Blargg tests continue to pass

v0.8.4 Released - December 28, 2025 - CPU/PPU Timing & Version Consistency!

Timing & Bug Fix Achievements:

CPU/PPU Timing: PPU now stepped BEFORE CPU cycle in tick() for accurate $2002 reads at VBlank
Version Consistency: Fixed About window (0.8.1) and Settings (0.8.2) showing outdated versions
Documentation: Fixed clone_mapper doctest by implementing full Clone for mapper Box types
Test Suite: 517+ tests passing (0 failures, 2 ignored for known architectural limitations)
100% Blargg Pass Rate: All 90/90 Blargg tests continue to pass

v0.8.3 Released - December 28, 2025 - Critical Rendering Bug Fix!

Critical Bug Fix Achievements:

Rendering Fix: Fixed framebuffer display showing "4 faint postage stamp copies" artifact
Palette Conversion: NES palette indices (0-63) now correctly converted to RGB using NES_PALETTE lookup table (64-entry)
Documentation: Changed 3 doctests from ignore to no_run for compile-time verification
Zero Regressions: 516+ tests passing, 100% Blargg pass rate maintained

v0.8.2 Released - December 28, 2025 - M10 Final Polish 50% Complete (UI/UX Improvements)!

M10 Sprint 1 Achievements:

Theme Support: Light/Dark/System themes with persistence and real-time switching
Status Bar: FPS counter (500ms updates), ROM name display, color-coded status messages (auto-expiry)
Tabbed Settings: Video/Audio/Input/Advanced tabs with comprehensive tooltips
Keyboard Shortcuts: Ctrl+O/P/R/Q, F1-F3, M for common operations
Modal Dialogs: Welcome screen, error dialogs, confirmation prompts, help window
Visual Feedback: Contextual tooltips, organized menus with separators
Zero Regressions: 508+ tests passing, 100% Blargg pass rate maintained

v0.8.1 Released - December 28, 2025 - M9 Known Issues Resolution 85% Complete!

M9 Sprint Achievements:

Audio Improvements (S1): Two-stage decimation via rubato, A/V sync with adaptive speed adjustment
PPU Edge Cases (S2): Sprite overflow, palette RAM mirroring, mid-scanline write detection
Performance Optimization (S3): #[inline] hints on CPU/PPU hot paths (step, execute_opcode, handle_nmi/irq)
Zero Regressions: 508+ tests passing, 100% Blargg pass rate maintained
Documentation: Updated all project files with v0.8.1 version references

v0.8.0 Released - December 28, 2025 - Rust 2024 Edition & Dependency Modernization!

Major Modernization Achievements:

Rust 2024 Edition: Full migration to Rust 2024 with MSRV 1.88+
Dependency Upgrades: eframe 0.33, egui 0.33, cpal 0.16, ron 0.12, rfd 0.15
Audio Resampling: rubato 0.16 integration for high-quality sample rate conversion
Performance: Inline hints and buffer reuse optimizations across APU subsystem

v0.7.1 Released - December 27, 2025 - Desktop GUI Framework Migration Complete!

GUI Framework Migration Achievements:

Framework Stack: Complete migration from Iced+wgpu to eframe+egui
Rendering: OpenGL backend via glow (replacing wgpu shader pipeline)
Audio: cpal 0.15 with lock-free ring buffer (8192 samples)
Input: gilrs 0.11 for gamepad support with hotplug detection
File Dialogs: rfd 0.15 for native cross-platform file dialogs
Configuration: ron 0.8 format with directories 5.0 for platform paths
Frame Timing: Accumulator-based timing at 60.0988 Hz NTSC
Debug Windows: CPU, PPU, APU, and Memory viewers (egui immediate mode)

v0.7.0 Released - December 21, 2025 - Milestone 8 Complete (100% Test Accuracy)!

Milestone 8 Achievements (COMPLETE):

CPU: 100% Blargg test pass rate (20/20). Cycle-accurate tick() implementation fixed all timing/IRQ edge cases.
PPU: 100% Blargg test pass rate (24/24). Fixed Open Bus, CHR-RAM routing, VBlank timing, Sprite Hits.
APU: 100% Blargg test pass rate (12/12). Fixed Frame Counter, DMC IRQ/DMA, Timer precision.
Mappers: 100% Mapper test pass rate (28/28). Validated NROM, MMC1, UxROM, CNROM, MMC3 IRQ.
Infrastructure: Robust test harness for all subsystems.

v0.6.0 Released - December 20, 2025 - Milestone 7 Complete!

Milestone 7 Achievements (COMPLETE):

CPU: All 256 opcodes verified (±1 cycle accuracy), page boundary crossing, unofficial opcodes
PPU: VBlank/NMI functional, sprite 0 hit working (2/2 tests), palette mirroring correct
APU: Frame counter precision fixed (22371→22372), hardware-accurate non-linear mixer
Bus: OAM DMA 513/514 cycle precision based on CPU cycle parity, CPU cycle tracking added

Milestone 8 Progress - ✅ COMPLETE (100% Blargg Pass Rate):

Blargg CPU Tests: 22/22 passing (100%) ✅
Blargg PPU Tests: 25/25 passing (100%) ✅
Blargg APU Tests: 15/15 passing (100%) ✅
Mapper Tests: 28/28 passing (100%) ✅
All previously known limitations RESOLVED (cpu_dummy_reads, cpu_interrupts) ✅
Tests: 508+ tests passing (0 failures, 0 ignored) ✅

v0.5.0 Released - December 19, 2025 - Phase 1 MVP Complete!

Major Milestones Completed:

M1 (CPU): 100% test pass rate - All 256 opcodes validated against nestest.nes golden log
M2 (PPU): 100% test pass rate - Complete 2C02 PPU with VBL/NMI and sprite hit working
M3 (APU): 100% test pass rate - All 5 audio channels implemented with cycle-accurate timing
M4 (Mappers): 100% test pass rate - 5 essential mappers covering 77.7% of licensed NES games
M5 (Integration): 100% test pass rate - Complete rustynes-core layer with Bus, Console, Input, Save State framework
M6 (Desktop GUI): Cross-platform Iced/wgpu application with ROM loading, audio playback, wgpu rendering, input handling
Test Suite: 392+ comprehensive tests passing across 6 crates (0 failures, 6 ignored)

Version History:

v0.1.0 (December 19, 2025): CPU + PPU - First official release with 129 tests passing
v0.2.0 (December 19, 2025): APU Complete - Added all 5 audio channels with 136 comprehensive tests
v0.3.0 (December 19, 2025): Mappers Complete - Added NROM, MMC1, UxROM, CNROM, MMC3 mappers with 78 tests
v0.4.0 (December 19, 2025): Integration Complete - Complete rustynes-core layer with 18 tests
v0.5.0 (December 19, 2025): Phase 1 MVP Complete - Desktop GUI with Iced/wgpu, audio playback (cpal), ROM loading, rendering, input
v0.6.0 (December 20, 2025): M7 Accuracy - Frame counter precision, hardware-accurate mixer, OAM DMA 513/514 cycles
v0.7.0 (December 21, 2025): M8 Test ROM Validation - 100% Blargg pass rate (90/90 tests)
v0.7.1 (December 27, 2025): GUI Framework Migration - Complete rewrite from Iced+wgpu to eframe+egui
v0.8.0 (December 28, 2025): Rust 2024 Edition - MSRV 1.88+, dependency modernization, audio resampling
v0.8.1 (December 28, 2025): M9 Known Issues (85%) - Audio S1, PPU S2, Performance S3 complete
v0.8.2 (December 28, 2025): M10 Final Polish (50%) - UI/UX improvements, theme support, tabbed settings
v0.8.3 (December 28, 2025): Critical Rendering Fix - Palette index to RGB conversion, doctest improvements
v0.8.4 (December 28, 2025): CPU/PPU Timing - PPU stepped before CPU cycle, version consistency fixes
v0.8.5 (December 29, 2025): M11 Sub-Cycle Accuracy (50%) - CpuBus trait, cpu.tick(), VBlank timing tests pass
v0.8.6 (December 29, 2025): M11 Sub-Cycle Accuracy (83%) - DMC DMA cycle stealing, open bus behavior, per-cycle mapper clocking

Project Status Change:

Phase 1 now 100% complete (all 6 milestones done)
MVP achieved ahead of original June 2026 target
Development shifting to Phase 2 advanced features

Progress Visualization:

Phase 1 (MVP):         ████████████████████ 100% (M1-M6 COMPLETE)
Phase 1.5 (Accuracy):  ██████████████████░░  96% (M7-M8 COMPLETE, M9 85%, M10 50%, M11 83%)

- M1: CPU           [████████████████████] 100% ✅ COMPLETED December 19, 2025
- M2: PPU           [████████████████████] 100% ✅ COMPLETED December 19, 2025
- M3: APU           [████████████████████] 100% ✅ COMPLETED December 19, 2025
- M4: Mappers       [████████████████████] 100% ✅ COMPLETED December 19, 2025
- M5: Integration   [████████████████████] 100% ✅ COMPLETED December 19, 2025
- M6: GUI           [████████████████████] 100% ✅ COMPLETED December 19, 2025
- M7: Accuracy      [████████████████████] 100% ✅ COMPLETED December 20, 2025
- M8: Test ROMs     [████████████████████] 100% ✅ COMPLETED December 21, 2025
- M11: Sub-Cycle    [████████████████░░░░]  83% 🔄 IN PROGRESS (S1-S5 Complete, S6 Pending)

Current Focus:

M7 (Accuracy) COMPLETE: CPU/PPU/APU timing improvements, OAM DMA precision ✅
M8 (Test ROM Validation) COMPLETE: 100% Blargg pass rate (CPU 22/22, PPU 25/25, APU 15/15, Mappers 28/28) ✅
M9 (Known Issues) 85% COMPLETE: Audio S1, PPU S2, Performance S3 complete ✅
M10-S1 (UI/UX Improvements) COMPLETE: Theme support, tabbed settings, status bar, keyboard shortcuts ✅
M11-S1 & S2 (Sub-Cycle Accuracy) COMPLETE: CpuBus trait, cpu.tick(), VBlank timing tests pass ✅
All known limitations resolved (cpu_dummy_reads, cpu_interrupts now passing) ✅
VBlank timing tests now pass with ±0 cycle accuracy ✅
520+ tests passing, 0 failures, 1 ignored ✅
Next: M11-S3 (Additional Test ROM Validation), M11-S4 (Performance Optimization)

Timeline Updates:

All Phase 1 milestones (M1-M6) completed December 19, 2025 (6+ months ahead of schedule)
MVP release achieved: December 2025 (accelerated from original June 2026 target)
Phase 2 development begins 2026

Overview

RustyNES development follows a phased approach with clear milestones and deliverables. Each phase builds upon the previous, ensuring a solid foundation before adding complexity. The roadmap targets v1.0 release within 24 months with 100% TASVideos accuracy.

Success Criteria

Metric	Phase 1 (MVP)	Phase 1.5 (Stabilization)	Phase 2 (Features)	Phase 3 (Expansion)	Phase 4 (v1.0)
Accuracy	5 tests passing	95%+ test ROMs (202/212)	95% TASVideos	98% TASVideos	100% TASVideos
Mappers	5 (77.7% games)	5 (77.7% games)	15 (95% games)	50 (99% games)	300+ (100%+)
Test Coverage	75%	85%	90%	92%	95%
Performance	100 FPS	120+ FPS	500 FPS	1000 FPS	1000+ FPS
Documentation	Core APIs	Complete	All APIs	Full guide	Complete
Audio Quality	Basic	High (A/V sync)	High	High	Professional
Stability	MVP	Production-ready	Stable	Robust	Rock-solid

Development Phases

gantt
    title RustyNES Development Timeline
    dateFormat YYYY-MM
    axisFormat %Y-%m

    section Phase 1: MVP
    CPU Implementation           :done, 2025-12, 1m
    PPU Implementation           :done, 2025-12, 1m
    APU Implementation           :done, 2025-12, 1m
    Basic Mappers (0-4)          :done, 2025-12, 1m
    Desktop GUI                  :done, 2025-12, 1m
    MVP Release (v0.5.0)         :milestone, 2025-12-19, 0d

    section Phase 1.5: Stabilization
    Accuracy Improvements        :2026-01, 1m
    Test ROM Validation          :2026-02, 1m
    Known Issues Resolution      :2026-03, 1m
    Final Polish                 :2026-04, 1m
    v1.0.0-alpha.1 Release       :milestone, 2026-04, 0d

    section Phase 2: Features
    RetroAchievements           :2026-05, 2m
    Netplay (GGPO)              :2026-06, 3m
    TAS Tools                   :2026-08, 2m
    Lua Scripting               :2026-09, 2m
    Debugger                    :2026-10, 2m
    Feature Complete            :milestone, 2026-12, 0d

    section Phase 3: Expansion
    Expansion Audio             :2027-01, 3m
    Additional Mappers          :2027-02, 4m
    WebAssembly                 :2027-04, 2m
    TAS Editor                  :2027-05, 2m
    Expansion Complete          :milestone, 2027-06, 0d

    section Phase 4: Polish
    Performance Optimization    :2027-07, 3m
    Video Filters               :2027-08, 2m
    Final Testing               :2027-09, 2m
    Documentation               :2027-10, 2m
    v1.0 Release                :milestone, 2027-12, 0d

Phase 1: MVP (Months 1-6)

Goal: Playable emulator with 80% game compatibility

Month 1: CPU Implementation - COMPLETED

Status: COMPLETED December 2025

Deliverables:

Cycle-accurate 6502 core
All official instructions (56 opcodes)
Unofficial opcodes (105 variants)
Interrupt handling (NMI, IRQ, BRK)
Pass nestest.nes golden log
19 additional Blargg CPU tests downloaded (awaiting integration)

Test Results:

nestest.nes: 100% match (5003+ instructions validated)
Unit tests: 46/46 passed
Integration tests: 1/1 passed (nestest_validation)
Total: 47/47 tests passing (100%)

Achievements:

All 256 opcodes (151 official + 105 unofficial) validated
Cycle-accurate timing confirmed
World-class CPU implementation

Acceptance Criteria:

100% nestest.nes match
All integrated tests pass
Unit tests for each instruction
Performance benchmarks established

Month 1: PPU Implementation - COMPLETED

Status: COMPLETED December 2025

Deliverables:

Dot-level rendering (341×262 scanlines)
Background rendering (pattern fetch, scrolling)
Sprite rendering (evaluation, priority, sprite 0 hit)
Accurate VBlank/NMI timing
Loopy scrolling model
25 additional PPU tests downloaded (awaiting integration)

Test Results:

Unit tests: 83/83 passed
Integration tests: 2/2 passed, 2/4 ignored (timing refinement)
Total: 85/87 tests passing, 2 ignored (97.7% pass rate, 100% passing or ignored)

Passing Test ROMs:

ppu_vbl_nmi.nes: Complete VBL/NMI suite
01-vbl_basics.nes: Basic VBlank behavior
01.basics.nes: Sprite 0 hit basics
02.alignment.nes: Sprite 0 hit alignment

Ignored (Not Failed) Tests:

02-vbl_set_time.nes: Requires ±51 cycle precision (timing refinement)
03-vbl_clear_time.nes: Requires ±10 cycle precision (timing refinement)

Achievements:

Cycle-accurate 2C02 PPU implementation
VBL/NMI timing working
Sprite 0 hit detection working
Excellent foundation for game compatibility

Acceptance Criteria:

Core PPU tests pass (97.8%)
VBlank/NMI timing accurate
Sprite 0 hit detection functional
Rendering pipeline complete

Month 2: Integration Testing (M5) - COMPLETED

Status: COMPLETED December 19, 2025

Completed Deliverables:

rustynes-core integration layer complete
Bus system with full NES memory map ($0000-$FFFF)
Console coordinator with timing synchronization
Cycle-accurate OAM DMA (513-514 cycles)
Input system with shift register protocol
Save state framework with format specification
18 comprehensive tests passing (100%)

Test Results:

Bus tests: 8/8 passing (100%)
Console tests: 3/3 passing (100%)
Controller tests: 4/4 passing (100%)
Integration tests: 3/3 passing (100%)
Total: 18/18 tests passing (100%)

Achievements:

Complete integration layer connecting all subsystems
Hardware-accurate bus implementation
Zero unsafe code maintained
Ready for M6 (Desktop GUI)

Acceptance Criteria:

Month 1: APU Implementation - COMPLETED

Status: COMPLETED December 19, 2025

Deliverables:

Pulse channels (duty, envelope, sweep)
Triangle channel (linear counter)
Noise channel (LFSR)
DMC channel (delta modulation)
Frame counter (4-step, 5-step)
Hardware-accurate mixing (non-linear lookup tables)
48 kHz output with resampling

Test Results:

Unit tests: 132/132 passed
Integration tests: 4/4 passed
Total: 136/136 tests passing (100%)

Achievements:

All 5 audio channels implemented (2 pulse, triangle, noise, DMC)
Cycle-accurate timing and frame counter
Non-linear mixing with authentic NES audio characteristics
Comprehensive test coverage across all channels
Zero unsafe code

Acceptance Criteria:

All APU channels implemented
Frame counter modes (4-step, 5-step) working
Non-linear mixing implemented
Comprehensive test coverage (136 tests)
Zero unsafe code maintained

Month 1: Mappers (M4) - COMPLETED

Status: COMPLETED December 19, 2025

Deliverables:

Test Results:

Unit tests: 78/78 passed
Integration tests: Pending M5
Total: 78/78 tests passing (100%)

Implementation Details:

3,401 lines of code across 9 source files
Complete mapper trait abstraction
iNES 1.0 and NES 2.0 ROM format parsing
Mirroring modes (horizontal, vertical, single-screen, four-screen)
MMC3 scanline IRQ with A12 edge detection
Zero unsafe code

Test Games Ready:

Super Mario Bros. (Mapper 0)
Legend of Zelda (Mapper 1)
Mega Man (Mapper 1)
Castlevania (Mapper 2)
Super Mario Bros. 3 (Mapper 4)

Acceptance Criteria:

All 5 mappers fully functional
77.7% game coverage (500+ titles)
Battery-backed SRAM support
Comprehensive test suite (78 tests)

Month 3-4: Desktop GUI (M6) - COMPLETED

Status: COMPLETED December 19, 2025 (v0.5.0), Migrated December 27, 2025 (v0.7.1)

Original Implementation (v0.5.0):

Iced-based interface with wgpu rendering

Current Implementation (v0.7.1 - eframe/egui):

eframe 0.29 + egui 0.29 immediate mode GUI
OpenGL rendering via glow backend
cpal 0.15 audio with lock-free ring buffer
Keyboard + gamepad input (gilrs 0.11)
Configuration persistence (ron 0.8 format)
Native file dialogs (rfd 0.15)
Debug windows (CPU, PPU, APU, Memory viewers)

Features:

Menu bar (File, Emulation, Video, Audio, Debug, Help)
Video settings (scaling modes: PixelPerfect, FitWindow, Integer)
Audio settings (volume control)
Controller configuration
Playback controls (pause, resume, reset)
Native ROM file browser

Acceptance Criteria:

60 FPS gameplay on mid-range hardware
No audio crackling
Gamepad auto-detection works
Cross-platform (Linux, Windows, macOS)

Phase 1 Milestone: MVP Release - ACHIEVED December 2025

Updated Timeline: Originally June 2026, achieved December 2025 (6+ months ahead of schedule!)

Release Checklist:

Phase 1.5: Stabilization & Accuracy (Months 7-9)

Goal: Achieve 95%+ test ROM pass rate and production-ready stability

Duration: 3-4 months (January-April 2026) Version Progression: v0.5.0 → v0.6.0 → v0.7.0 → v0.8.0 → v0.9.0/v1.0.0-alpha.1

Phase 1.5 bridges Phase 1 MVP (v0.5.0) to Phase 2 Advanced Features, focusing on accuracy improvements, comprehensive test ROM validation, and resolving all known issues from the MVP release.

Overview

Current State (v0.5.0):

Phase 1 MVP complete (all 6 milestones)
5 test ROMs passing, ~200 pending integration
VBlank timing ±51 cycles (target: ±2 cycles)
Audio quality issues (pops, clicks, A/V sync drift)
No comprehensive performance benchmarking

Target State (v0.9.0/v1.0.0-alpha.1):

95%+ test ROM pass rate (202+/212 tests)
VBlank timing ±2 cycles
High-quality audio (no artifacts, perfect A/V sync)
20%+ performance improvement (120+ FPS)
Zero critical bugs
Production-ready for Phase 2 advanced features

Milestone 7: Accuracy Improvements (v0.6.0) - COMPLETE

Duration: December 20, 2025 Status: ✅ COMPLETED Focus: CPU, PPU, APU, Bus timing refinements

Objectives:

CPU timing refinements (±1 cycle accuracy) ✅
[~] PPU VBlank precision (functional, cycle-precise deferred to Phase 2+)
APU frame counter precision (±1 cycle) ✅
Bus timing accuracy (OAM DMA 513-514 cycles) ✅

Key Achievements:

CPU: All 256 opcodes verified (±1 cycle accuracy), page boundary crossing, unofficial opcodes
PPU: VBlank/NMI functional, sprite 0 hit working (2/2 tests), palette mirroring correct
APU: Frame counter 4-step mode fixed (22371→22372), hardware-accurate non-linear mixer
Bus: OAM DMA 513/514 cycle precision based on CPU cycle parity, CPU cycle tracking added

Test Results: 429 tests passing (0 failures, 6 ignored for valid reasons)

Deliverable: v0.6.0 released December 20, 2025

Sprint Breakdown:

Sprint 1: CPU Accuracy ✅ COMPLETE
- All 256 opcodes verified against NESdev specification
- Page boundary crossing accuracy confirmed
- Unofficial opcode timing validated
Sprint 2: PPU Accuracy ✅ COMPLETE
- VBlank/NMI timing functional (cycle-precise deferred)
- Sprite 0 hit basic tests passing (2/2)
- Palette RAM mirroring verified
Sprint 3: APU Accuracy ✅ COMPLETE
- Frame counter precision fixed (22371→22372)
- Hardware-accurate non-linear mixer implemented
- TND channel divisors corrected
Sprint 4: Bus & Timing Polish ✅ COMPLETE
- OAM DMA 513/514 cycle precision (based on CPU cycle parity)
- CPU cycle tracking added to bus
- CPU/PPU synchronization verified (3:1 ratio)

Milestone 8: Test ROM Validation (v0.7.0) - ✅ COMPLETE

Duration: December 21, 2025 (1 day - accelerated from 1 month target) Focus: Systematic test ROM integration and validation Status: ✅ COMPLETE - 100% Blargg Pass Rate Achieved

Objectives:

Integrate all Blargg test ROMs into automated test harness (90 total tests)
Achieve 100% Blargg test pass rate (90/90 tests) - EXCEEDED 95% target
Document all test failures with root cause analysis (800+ line technical doc)
CI pipeline runs full test suite

Test ROM Coverage (COMPLETE):

Blargg CPU: 22/22 tests passing (100%) ✅ COMPLETE
- All 11 cpu_instr tests passing
- cpu_dummy_reads passing (was known limitation)
- cpu_interrupts passing (all 5 sub-tests, was known limitation)
- cpu_dummy_writes_ppumem, cpu_dummy_writes_oam passing
- cpu_all_instrs, cpu_official_only, cpu_instr_timing passing
- cpu_exec_space_ppuio, cpu_exec_space_apu passing
Blargg PPU: 25/25 tests passing (100%) ✅ COMPLETE
- ppu_vbl_nmi suite (10 tests) passing
- ppu_sprite_hit (2 tests) passing
- ppu_open_bus passing
- ppu_palette_ram passing
- CHR-RAM routing fixes enabling previously failing tests
Blargg APU: 15/15 tests passing (100%) ✅ COMPLETE
- apu_test suite (11 tests) passing
- apu_dmc_basics, apu_dmc_rates passing
- apu_len_ctr, apu_irq_flag_timing passing
Mapper Tests: 28/28 tests passing (100%) ✅ COMPLETE
- NROM (Mapper 0), MMC1 (Mapper 1), UxROM (Mapper 2)
- CNROM (Mapper 3), MMC3 (Mapper 4)
Total: 90/90 Blargg tests passing (100% pass rate) ✅ EXCEEDED TARGET

Deliverable: v0.7.0 released December 21, 2025 with 100% Blargg pass rate

Sprint Breakdown (All Completed):

Sprint 1: CPU Accuracy Improvements (22/22 tests) ✅
- Cycle-accurate CPU tick() state machine
- NMI hijacking during BRK instruction
- Dummy read/write cycles for implied addressing modes
Sprint 2: PPU Accuracy Improvements (25/25 tests) ✅
- PPU open bus emulation with data latch
- CHR-RAM routing architecture fix
- VBlank/NMI timing precision
Sprint 3: APU Accuracy Improvements (15/15 tests) ✅
- Frame counter immediate clocking
- DMC sample buffer refill logic
- Timer precision fixes
Sprint 4: Mapper Validation (28/28 tests) ✅
- All 5 mappers validated
- Banking logic, mirroring, IRQ timing verified

Milestone 9: Known Issues Resolution (v0.8.0)

Duration: 1 month (December 2025 - January 2026) Focus: Audio quality, PPU edge cases, performance optimization, bug fixes Status: Sprint 0 Complete (v0.8.0), Sprints 1-4 In Progress

Sprint 0 - Dependency Upgrade (v0.8.0) - COMPLETE December 28, 2025:

Rust 2024 Edition migration (MSRV 1.88+)
eframe 0.29 → 0.33, egui 0.29 → 0.33
cpal 0.15 → 0.16, ron 0.8 → 0.12, rfd 0.14 → 0.15
rubato 0.16 integration for audio resampling
Inline hints and buffer reuse optimizations
508+ tests passing (0 failures, 0 ignored)

Objectives (Sprints 1-4):

Dynamic audio resampling (rubato) - PARTIALLY COMPLETE
Audio/video synchronization
PPU edge case fixes (sprite overflow, palette RAM)
20%+ performance improvement (100 FPS → 120+ FPS)
Fix all critical bugs from GitHub issues

Audio Improvements:

Dynamic resampling (NES 1.789773 MHz → PC 48 kHz)
Ring buffer management (prevent underrun/overflow)
Audio/video sync (frame callback timing)
Zero audio pops/clicks/crackling

PPU Edge Cases:

Sprite overflow flag edge cases
Palette RAM reads ($3F04, $3F08, $3F0C)
Mid-scanline scrolling changes
Sprite 0 hit timing precision

Performance Optimization:

Profiling with cargo-flamegraph
Benchmarking with criterion
Hot path optimization
Target: 120+ FPS (20%+ improvement)

Deliverable: v0.8.0 with high-quality audio, PPU fixes, and optimized performance

Sprint Breakdown:

Sprint 0: Dependency Upgrade (v0.8.0) ✅ COMPLETE
- Rust 2024 Edition migration (MSRV 1.88+)
- Framework upgrades (eframe 0.33, egui 0.33, cpal 0.16)
- Audio resampling foundation (rubato 0.16)
- Performance optimizations (inline hints, buffer reuse)
Sprint 1: Audio Improvements (1 week)
- Dynamic resampling implementation
- A/V synchronization
- Buffer management
Sprint 2: PPU Edge Cases (1 week)
- Sprite overflow flag
- Palette RAM edge cases
- Scrolling edge cases
Sprint 3: Performance Optimization (1 week)
- Profiling and benchmarking
- Hot path optimization
- 20%+ performance improvement
Sprint 4: Bug Fixes & Polish (1 week)
- GitHub issue triage
- Critical bug fixes
- Error handling improvements

Milestone 10: Final Polish (v0.9.0/v1.0.0-alpha.1)

Duration: 1 week (April 2026) Focus: UI/UX polish, documentation, release preparation

Objectives:

UI/UX improvements (responsive design, theme support)
Comprehensive documentation (user guide, API docs, developer guide)
Full regression testing (202/212 tests, 95%+)
Build release binaries (Linux, macOS, Windows)
Decide version number (v0.9.0 or v1.0.0-alpha.1)
Publish GitHub release

UI/UX Improvements:

Responsive layout (adapt to window size)
Theme support (light/dark mode)
Improved settings organization
Visual feedback (loading states, progress bars)
Accessibility (keyboard navigation, screen reader support)

Documentation:

User guide (installation, usage, troubleshooting)
API documentation (rustdoc for all public APIs)
Developer guide (architecture, testing, contributing)
Known limitations and workarounds
FAQ

Version Decision:

v0.9.0: If 90-94% test pass rate, minor issues remaining
v1.0.0-alpha.1: If 95%+ test pass rate, zero critical bugs, documentation complete

Deliverable: v0.9.0 or v1.0.0-alpha.1 with polished UI, complete documentation, and multi-platform release

Sprint Breakdown:

Sprint 1: UI/UX Improvements (2 days)
- Responsive design
- Theme support
- Settings organization
Sprint 2: Documentation (3 days)
- User guide
- API documentation
- Developer guide
Sprint 3: Release Preparation (2 days)
- Full regression testing
- Binary builds
- GitHub release

Phase 1.5 Milestone: Stabilization Complete

Release Checklist:

Transition to Phase 2:

Phase 1.5 establishes a production-ready foundation for Phase 2 advanced features (RetroAchievements, netplay, TAS tools). With 95%+ accuracy and zero critical bugs, the emulator is ready for community use and advanced feature development.

Phase 2: Advanced Features (Months 10-15)

Goal: Feature parity with modern emulators

Month 7-8: RetroAchievements

Deliverables:

Acceptance Criteria:

Achievements unlock correctly in 10 test games
No false positives/negatives
Leaderboard submissions work
<1% performance impact

Month 7-9: Netplay (GGPO)

Deliverables:

Acceptance Criteria:

1-2 frame input lag over LAN
<5 frame rollback on 100ms ping
No desyncs in 30-minute sessions
Works behind typical NAT setups

Month 8-9: TAS Tools

Deliverables:

Acceptance Criteria:

Can record and replay TAS movies
Deterministic execution (same inputs → same output)
Frame-perfect input timing
Compatible with FCEUX FM2 format

Month 9-10: Lua Scripting

Deliverables:

Acceptance Criteria:

Can read/write RAM from Lua
Frame callbacks work at 60 Hz
Drawing primitives render correctly
<5% performance overhead

Month 10-11: Advanced Debugger

Deliverables:

CPU debugger (disassembly, breakpoints, stepping)
PPU viewer (nametables, pattern tables, palettes, OAM)
APU viewer (channel waveforms, volume meters)
Memory viewer/editor (hex dump, search)
Trace logger
Code-data logger (CDL)

Acceptance Criteria:

Breakpoints work reliably
PPU viewer updates in real-time
Trace logger captures execution
Useful for homebrew debugging

Month 11-12: Quality of Life

Deliverables:

Acceptance Criteria:

Rewind goes back 10+ seconds
Fast-forward reaches 10x speed
Cheats apply correctly
Video recording at 60 FPS

Phase 2 Milestone: Feature Complete

Release Checklist:

Pass 95% of TASVideos test suite
All advanced features functional
API documentation complete
Tutorial videos recorded
Community Discord server launched

Phase 3: Expansion (Months 13-18)

Goal: Comprehensive mapper support and platform expansion

Month 13-15: Expansion Audio

Deliverables:

Test Games:

Castlevania III (VRC6)
Lagrange Point (VRC7)
Castlevania (FDS)

Acceptance Criteria:

Expansion audio sounds accurate
Music matches hardware recordings
Proper channel mixing

Month 14-17: Additional Mappers

Target: 98% game coverage (50 total mappers)

Priority Mappers:

Acceptance Criteria:

All target games playable
Mapper-specific test ROMs pass
IRQ timing accurate

Month 16-17: WebAssembly

Deliverables:

Acceptance Criteria:

Runs in Chrome, Firefox, Safari
60 FPS on desktop browsers
30+ FPS on mobile
ROMs load from local files

Month 17-18: TAS Editor

Deliverables:

Acceptance Criteria:

Can create/edit TAS movies
Greenzone manages 10,000+ frames
Branching works reliably
Competitive with FCEUX TAS editor

Phase 3 Milestone: Expansion Complete

Release Checklist:

Pass 98% of TASVideos test suite
99%+ game compatibility
WebAssembly demo live
Expansion audio demo videos

Phase 4: Polish & Release (Months 19-24)

Goal: Production-ready v1.0 release

Month 19-21: Performance Optimization

Targets:

1000+ FPS (16x real-time) on modern CPUs
<100 MB memory footprint
<5ms frame time
<10ms audio latency

Optimizations:

CPU: Jump table dispatch, inline hot paths
PPU: SIMD pixel compositing, batch rendering
APU: Fast sinc resampling, SSE/NEON mixing
Mappers: Precomputed banking tables

Profiling:

Criterion benchmarks for all components
Flamegraph analysis
Cache misses optimization

Month 20-21: Video Filters

Deliverables:

NTSC filter (Blargg)
CRT shader (scanlines, curvature, bloom)
Palette options (Composite, RGB, Custom)
Aspect ratio modes (4:3, Pixel Perfect, Stretch)
Overscan cropping

Acceptance Criteria:

Filters look authentic
<2ms overhead per frame
User-adjustable parameters

Month 21-22: Final Testing

Test Plan:

Bug Fixes:

Prioritize by severity
Test coverage for all fixes
Regression prevention

Month 22-23: Documentation

Deliverables:

Topics:

Getting started
Configuration
Advanced features (TAS, netplay, debugging)
Troubleshooting
Contributing guide

Month 24: v1.0 Release

Release Checklist:

Launch Activities:

Milestone Tracking

Current Status (Phase 1 MVP Complete - December 2025)

Phase 1 Progress: 100% Complete - All 6 milestones complete, MVP achieved! Phase 1.5 Progress: 50% Complete - M7 complete, M8 90% done (Blargg CPU)

Component	Status	Progress	Test Results
Architecture Design	Complete	100%	N/A
Documentation	Complete (40+ files)	100%	N/A
Workspace Structure	Complete (10 crates)	100%	N/A
CPU (M1)	COMPLETE	100%	267/267 passing (100%)
PPU (M2)	COMPLETE	100%	90/90 passing (100%)
APU (M3)	COMPLETE	100%	150/150 passing (100%)
Mappers (M4)	COMPLETE	100%	167/167 passing (100%)
Integration (M5)	COMPLETE	100%	23/23 passing (100%)
GUI (M6)	COMPLETE	100%	Cross-platform eframe/egui (v0.7.1)
Blargg Tests (M8)	COMPLETE	100%	90/90 passing (100% - CPU 22, PPU 25, APU 15, Mappers 28)

Detailed Component Status

M1: CPU Implementation - COMPLETED December 2025

Status: All acceptance criteria met, world-class implementation

All 256 opcodes (151 official + 105 unofficial) validated
nestest.nes: 100% golden log match (5003+ instructions)
Unit tests: 46/46 passing
Integration tests: 1/1 passing
Total: 47/47 tests passing (100%)

M2: PPU Implementation - COMPLETED December 2025

Status: Excellent implementation, cycle-accurate 2C02 PPU

Cycle-accurate 2C02 PPU
VBL/NMI timing working
Sprite 0 hit detection functional
Unit tests: 83/83 passing
Integration tests: 2/2 passing, 2/4 ignored (timing refinement)
Total: 85/87 tests passing (97.7%), 2 ignored

M3: APU Implementation - COMPLETED December 19, 2025

Status: All acceptance criteria met, comprehensive implementation

All 5 audio channels implemented (2 pulse, triangle, noise, DMC)
Cycle-accurate timing and frame counter (4-step, 5-step)
Non-linear mixing with authentic NES audio characteristics
Hardware-accurate envelope, sweep, and length counter
DMC channel with memory reader and sample playback
Unit tests: 132/132 passing
Integration tests: 4/4 passing
Total: 136/136 tests passing (100%)

M4: Mapper Implementation - COMPLETED December 19, 2025

Status: All acceptance criteria met, comprehensive implementation

5 essential mappers (NROM, MMC1, UxROM, CNROM, MMC3)
77.7% licensed NES game coverage (500+ titles)
Complete iNES 1.0 and NES 2.0 ROM format parsing
All mirroring modes (horizontal, vertical, single-screen, four-screen)
MMC3 scanline IRQ with A12 edge detection
Battery-backed SRAM support
Unit tests: 78/78 passing
Total: 78/78 tests passing (100%)

M5: Integration Testing - COMPLETED December 19, 2025

Status: All acceptance criteria met, production-ready integration layer

Complete rustynes-core integration layer
Hardware-accurate bus system with full NES memory map
Console coordinator with timing synchronization
Cycle-accurate OAM DMA (513-514 cycles)
Input system with shift register protocol
Save state framework with format specification
Total: 18/18 tests passing (100%)

Achievements:

Zero unsafe code maintained
All subsystems integrated (CPU, PPU, APU, Mappers)
Ready for M6 (Desktop GUI)

M6: Desktop GUI - COMPLETED December 19, 2025 (Migrated v0.7.1)

Status: All acceptance criteria met, cross-platform desktop application

Original (v0.5.0): Iced + wgpu rendering

Current (v0.7.1): Complete GUI framework migration to eframe + egui

eframe 0.29 + egui 0.29 immediate mode GUI
OpenGL rendering via glow backend (replaced wgpu shader pipeline)
ROM loading with native file dialogs (rfd 0.15)
Accumulator-based frame timing at 60.0988 Hz NTSC
cpal 0.15 audio with lock-free ring buffer (8192 samples)
Keyboard and gamepad input (gilrs 0.11)
Configuration persistence (ron 0.8 format)
Debug windows: CPU, PPU, APU, Memory viewers
Total: Cross-platform MVP release with improved architecture

Achievements:

Zero unsafe code maintained across 6 crates
Complete Phase 1 MVP achieved
GUI framework migrated for better immediate mode support
6+ months ahead of original schedule

Key Milestones

Phase 1: MVP (v0.1.0 - v0.5.0)

M1: CPU passes nestest.nes - COMPLETED December 19, 2025
M2: PPU renders first frame - COMPLETED December 19, 2025
M3: APU outputs audio - COMPLETED December 19, 2025
M4: Mappers functional - COMPLETED December 19, 2025
M5: Integration testing complete - COMPLETED December 19, 2025
M6: Desktop GUI - COMPLETED December 19, 2025
MVP: First playable release (v0.5.0) - ACHIEVED December 19, 2025

Phase 1.5: Stabilization & Accuracy (v0.6.0 - v1.0.0-alpha.1)

M7: Accuracy improvements (v0.6.0) - ✅ COMPLETED December 20, 2025
M8: Test ROM validation (v0.7.0, 100% Blargg pass rate) - ✅ COMPLETED December 21, 2025
M9: Known issues resolution (v0.8.0) - PLANNED January 2026
M10: Final polish (v0.9.0/v1.0.0-alpha.1) - PLANNED February 2026
Stabilization Complete: Production-ready release - TARGET February 2026

Phase 2: Advanced Features (v1.1.0 - v1.5.0)

M11: RetroAchievements working - PLANNED May-June 2026
M12: Netplay functional - PLANNED July-September 2026
M13: TAS Tools - PLANNED August-September 2026
M14: Lua Scripting - PLANNED September-October 2026
M15: Advanced Debugger - PLANNED October-November 2026
Feature Complete - TARGET December 2026

Phase 3: Expansion (v1.6.0 - v1.9.0)

M16: Expansion audio - PLANNED January-March 2027
M17: Additional mappers (50 total) - PLANNED February-May 2027
M18: WebAssembly - PLANNED April-May 2027
M19: TAS Editor - PLANNED May-June 2027
Expansion Complete - TARGET June 2027

Phase 4: Polish & Release (v1.10.0 - v1.0)

M20: Performance optimization - PLANNED July-September 2027
M21: Video filters - PLANNED August-September 2027
M22: Final testing & documentation - PLANNED September-November 2027
v1.0 Release - TARGET December 2027

Current Sprint Focus (Phase 1.5 Planning)

Priority: Phase 1.5 stabilization and accuracy improvements

Phase 1 - COMPLETED December 19, 2025

All Phase 1 milestones completed ahead of schedule:

M1: CPU Implementation - DONE (December 19, 2025)
M2: PPU Implementation - DONE (December 19, 2025)
M3: APU Implementation - DONE (December 19, 2025)
M4: Mapper Implementation - DONE (December 19, 2025)
M5: Integration Layer - DONE (December 19, 2025)
M6: Desktop GUI - DONE (December 19, 2025)

Achievement: Complete MVP emulator with 6 crates, 508+ tests (as of v0.8.0), zero unsafe code

Phase 1.5 Planning

Duration: January-April 2026 (3-4 months)

Objective: Production-ready emulator with 95%+ accuracy

Planned Milestones:

M7: Accuracy Improvements (v0.6.0) - January 2026
- CPU timing refinements (±1 cycle)
- PPU VBlank precision (±2 cycles)
- APU frame counter precision
- Bus timing accuracy
M8: Test ROM Validation (v0.7.0) - February 2026
- Integrate all 212 test ROMs
- Achieve 95%+ pass rate (202+/212 tests)
- Automated test harness
- CI pipeline integration
M9: Known Issues Resolution (v0.8.0) - March 2026
- Dynamic audio resampling
- Audio/video synchronization
- PPU edge case fixes
- 20%+ performance improvement
M10: Final Polish (v0.9.0/v1.0.0-alpha.1) - April 2026
- UI/UX improvements
- Comprehensive documentation
- Multi-platform release binaries
- Production-ready release

Deliverable: Stable, accurate emulator ready for Phase 2 advanced features

Transition to Phase 2: With 95%+ accuracy and zero critical bugs, begin RetroAchievements, netplay, and TAS tools development in May 2026.

Risk & Blockers

Current Status

No Critical Blockers - Phase 1 MVP complete, ready for Phase 1.5 stabilization

Phase 1.5 Priorities

M7: Accuracy Improvements - January 2026
- VBlank timing precision (±51 cycles → ±2 cycles)
- CPU/PPU/APU timing refinements
- Pass currently-ignored timing tests
M8: Test ROM Validation - February 2026
- Integrate 212 test ROMs into automated harness
- Achieve 95%+ pass rate (202+/212 tests)
- Document failure root causes
M9: Known Issues Resolution - March 2026
- Dynamic audio resampling (eliminate pops/clicks)
- PPU edge case fixes
- 20%+ performance improvement
M10: Final Polish - April 2026
- UI/UX improvements
- Comprehensive documentation
- Multi-platform release

Project Health

Phase 1 MVP complete (all 6 milestones) - 6+ months ahead of schedule
400+ comprehensive tests passing across 6 crates
Zero unsafe code maintained across all crates
Cross-platform desktop application released
Phase 1.5 planning complete with detailed sprint documentation
Strong foundation for accuracy improvements and advanced features

Feature Priorities

P0 (Critical - MVP Blockers)

Cycle-accurate CPU
Dot-level PPU
APU with all 5 channels
Mappers 0, 1, 2, 3, 4
Desktop GUI
Save states

P1 (High - Post-MVP)

RetroAchievements
Netplay
TAS recording
Lua scripting
Advanced debugger
Rewind

P2 (Medium - Expansion)

Expansion audio
50 total mappers
WebAssembly
TAS editor
Video filters

P3 (Low - Polish)

300+ mappers
Performance optimizations
Advanced shaders
Steam integration
Mobile builds

Testing Strategy

Unit Tests

CPU: Each instruction
PPU: Rendering functions
APU: Channel outputs
Mappers: Banking logic

Target: 95% code coverage

Current Status: 508+ tests passing across all 6 crates (as of v0.8.0)

rustynes-cpu: 47 tests (46 unit + 1 integration) - 100% passing
rustynes-ppu: 85 tests (83 unit + 4 integration, 2 ignored) - 97.7% pass rate
rustynes-apu: 136 tests (132 unit + 4 integration) - 100% passing
rustynes-mappers: 78 tests (78 unit) - 100% passing
rustynes-core: 18 tests (18 unit) - 100% passing
rustynes-desktop: Cross-platform GUI integration tests
Doctests: 32 passing, 4 ignored (file I/O constraints)

Integration Tests

CPU+Bus interactions
PPU+Mapper interactions
Full frame execution
Save state serialization

Current Status: All integration tests passing in rustynes-core

Test ROM Validation

Comprehensive Test ROM Collection: 212 test files (172 unique after deduplication)

See tests/TEST_ROM_PLAN.md for complete test execution plan.

Test ROM Inventory:

CPU: 36 test ROMs (1 integrated: nestest.nes passing, 35 pending)
PPU: 49 test ROMs (6 integrated: 4 passing, 2 ignored for timing, 43 pending)
APU: 70 test ROMs (all pending integration)
Mappers: 57 test ROMs (all pending integration)

Essential (Currently Passing):

nestest.nes (100% golden log match - 5003+ instructions validated)
ppu_vbl_nmi.nes (VBL/NMI timing test suite)
ppu_01-vbl_basics.nes (basic VBlank behavior)
ppu_01.basics.nes (sprite 0 hit basics)
ppu_02.alignment.nes (sprite 0 hit alignment)

Pending Integration (212 test ROMs):

Blargg CPU instruction tests (11 ROMs)
Blargg CPU timing tests (3 ROMs)
Blargg PPU VBL/NMI tests (7 ROMs)
Quietust sprite hit tests (11 ROMs)
Blargg APU test suite (70 ROMs)
Holy Mapperel mapper tests (45 ROMs)
MMC3/MMC5 specialized tests (16 ROMs)

Integration Target:

Phase 1 (MVP): 75%+ pass rate (154/184 implemented test ROMs)
Phase 2 (Features): 85%+ pass rate
Phase 3 (Expansion): 95%+ pass rate
Phase 4 (v1.0): 100% TASVideos accuracy suite (156 tests)
sprite_hit_tests_2005.10.05
vbl_nmi_timing

Game Compatibility Testing

Per Mapper:

10 commercial games
5 homebrew games
Known edge cases

Regression Testing:

CI pipeline runs on every commit
Automated save state comparison
Frame-by-frame screenshot diffing

Conclusion

This roadmap balances ambition with realism, targeting v1.0 in 24 months with aggressive but achievable milestones. The phased approach ensures continuous value delivery, with each phase building upon a solid foundation.

Current Progress Summary

RustyNES development has achieved a major milestone with Phase 1 MVP complete and GUI framework migration in v0.7.1:

Achievements to Date:

World-class CPU implementation: 100% test pass rate (47/47 tests)
Excellent PPU implementation: 100% test pass rate (90/90 tests)
Comprehensive APU implementation: 100% test pass rate (150/150 tests)
Complete Mapper subsystem: 100% test pass rate (167/167 tests)
Production-ready Integration layer: 100% test pass rate (23/23 tests)
Cross-platform Desktop GUI with eframe/egui (v0.8.0)
5 mappers covering 77.7% of licensed NES games (500+ titles)
508+ total tests passing across 6 crates
100% Blargg test pass rate (90/90 tests)
Zero unsafe code across all 6 crates
Complete playable MVP with GUI framework migration and Rust 2024 modernization (v0.8.0)

Current Status:

Phase 1 is 100% complete (all 6 milestones done)
Phase 1.5 Milestones M7-M8 complete (100% Blargg pass rate)
Phase 1.5 Milestone M9-S0 complete (Rust 2024 Edition, dependency modernization)
MVP achieved 6+ months ahead of original June 2026 target
GUI framework migration complete (Iced+wgpu to eframe+egui)
v0.8.0 released December 28, 2025 (Rust 2024 Edition)

Phase 1.5 Priorities:

With M7-M8 complete, development focuses on remaining stabilization:

M7: Accuracy improvements (CPU/PPU/APU timing refinements) - COMPLETE
M8: Test ROM validation (100% Blargg pass rate achieved) - COMPLETE
M9: Known issues resolution (audio quality, PPU edge cases, performance)
M10: Final polish (UI/UX, documentation, multi-platform release)
Target: v0.9.0 or v1.0.0-alpha.1 by April 2026

Transition to Phase 2: May 2026 (RetroAchievements, netplay, TAS tools)

What Makes This Significant:

6+ months ahead of original schedule
508+ comprehensive tests passing across 6 crates
100% Blargg test pass rate (90/90 tests)
Zero unsafe code across all crates
Cycle-accurate CPU, PPU, APU, Mapper, and Integration implementations
77.7% game compatibility with cross-platform desktop application
Phase 1 MVP complete with GUI framework migration (eframe+egui)
Rust 2024 Edition with MSRV 1.88+ and modernized dependencies (v0.8.0)

Success continues to depend on:

Rigorous testing (test ROMs, real games, edge cases)
Performance profiling (optimize after correctness)
Clear documentation (lowering contribution barriers)
Community involvement (testing, feedback, contributions)

Next Steps: Continue Phase 1.5 stabilization (M9-M10) with v0.8.0 foundation before advanced features in Phase 2!

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RustyNES Development Roadmap

Table of Contents

Recent Updates (v2.15.0 - December 2025)

Overview

Success Criteria

Development Phases

Phase 1: MVP (Months 1-6)

Month 1: CPU Implementation - COMPLETED

Month 1: PPU Implementation - COMPLETED

Month 2: Integration Testing (M5) - COMPLETED

Month 1: APU Implementation - COMPLETED

Month 1: Mappers (M4) - COMPLETED

Month 3-4: Desktop GUI (M6) - COMPLETED

Phase 1 Milestone: MVP Release - ACHIEVED December 2025

Phase 1.5: Stabilization & Accuracy (Months 7-9)

Overview

Milestone 7: Accuracy Improvements (v0.6.0) - COMPLETE

Milestone 8: Test ROM Validation (v0.7.0) - ✅ COMPLETE

Milestone 9: Known Issues Resolution (v0.8.0)

Milestone 10: Final Polish (v0.9.0/v1.0.0-alpha.1)

Phase 1.5 Milestone: Stabilization Complete

Phase 2: Advanced Features (Months 10-15)

Month 7-8: RetroAchievements

Month 7-9: Netplay (GGPO)

Month 8-9: TAS Tools

Month 9-10: Lua Scripting

Month 10-11: Advanced Debugger

Month 11-12: Quality of Life

Phase 2 Milestone: Feature Complete

Phase 3: Expansion (Months 13-18)

Month 13-15: Expansion Audio

Month 14-17: Additional Mappers

Month 16-17: WebAssembly

Month 17-18: TAS Editor

Phase 3 Milestone: Expansion Complete

Phase 4: Polish & Release (Months 19-24)

Month 19-21: Performance Optimization

Month 20-21: Video Filters

Month 21-22: Final Testing

Month 22-23: Documentation

Month 24: v1.0 Release

Milestone Tracking

Current Status (Phase 1 MVP Complete - December 2025)

Detailed Component Status

M1: CPU Implementation - COMPLETED December 2025

M2: PPU Implementation - COMPLETED December 2025

M3: APU Implementation - COMPLETED December 19, 2025

M4: Mapper Implementation - COMPLETED December 19, 2025

M5: Integration Testing - COMPLETED December 19, 2025

M6: Desktop GUI - COMPLETED December 19, 2025 (Migrated v0.7.1)

Key Milestones

Phase 1: MVP (v0.1.0 - v0.5.0)

Phase 1.5: Stabilization & Accuracy (v0.6.0 - v1.0.0-alpha.1)

Phase 2: Advanced Features (v1.1.0 - v1.5.0)

Phase 3: Expansion (v1.6.0 - v1.9.0)

Phase 4: Polish & Release (v1.10.0 - v1.0)

Current Sprint Focus (Phase 1.5 Planning)

Phase 1 - COMPLETED December 19, 2025

Phase 1.5 Planning

Risk & Blockers

Current Status

Phase 1.5 Priorities

Project Health

Feature Priorities

P0 (Critical - MVP Blockers)

P1 (High - Post-MVP)

P2 (Medium - Expansion)

P3 (Low - Polish)

Testing Strategy

Unit Tests

Integration Tests

Test ROM Validation

Game Compatibility Testing