No source code. Reverse engineered from xex binary and ported to nes via gbdk by DeepSeek v4.1 FLASH and Sonnet 5.5 Mostly Altirra and AltirraBridge was used. REA with Ghidra for some minor extractions.
WIP.
Playable: the procedural river (exact Atari generator, bridges and roads), the jet,
the shot, ships, helicopters, jets, fuel depots, the bridge tank and its shell, a
source-faithful HUD, scoring and lives all work. Still open: sound, respawn at the
last bridge, exact fuel rate and some entity-placement details (see PROGRESS.md).
Performance: the river scrolls at 60 Hz, the game logic runs at 30 Hz. On NTSC the NES has about 29,780 CPU cycles per frame and the faked scanline split spends ~5.4k of them, so the hot paths are hand-written 6502. Cruise flight is smooth (about 0.5% late frames), fast flight (1.5 px/frame) is playable.
./build.ps1 # roms/river_raid.nes (must be 65,552 bytes), .noi, .map
node tests/nes_smoke.mjs # Mesen checks (start MesenCE-MCP first, see AGENTS.md)
./tests/host_river.ps1 # C generator vs. the Python model (needs zig)HANDOFF.md is the short current status and next steps, AGENTS.md the toolchain
rules, info/LESSONS.md the detailed lessons learned, PROGRESS.md the history
log, PORTING_PLAN.md the roadmap.
