Port 'From Below' NES game to C# with dotnes

[jonathanpeppers]

Port the open-source NES homebrew game From Below by Matt Hughson from C (cc65/neslib) to C# using dotnes.

Source repo: https://github.com/mhughson/mbh-firstnes
License: MIT
Original language: C with cc65 + neslib + nesdoug
ROM specs: NROM (mapper 0), 32KB PRG, 8KB CHR, horizontal mirroring

This is the ideal candidate for a dotnes port because:

• It uses neslib, which dotnes is based on
• The source is open and MIT-licensed
• It is a real, commercially sold NES game (physical cartridges)
• It exercises many neslib APIs: palettes, sprites, VRAM updates, pad input, music/SFX (FamiTone)

The dotnes decompiler can extract the project skeleton and CHR tile data, but the game logic (~92KB of C) needs manual/AI-assisted porting from C to C#.

Approach:

1. Use the decompiler to generate the project scaffold and CHR data
2. Port game/main.c and game/main.h to idiomatic dotnes C# using neslib APIs
3. Identify any missing neslib APIs needed and add them
4. Verify the output ROM matches the original behavior