Gomu is a Nintendo Entertainment System (NES) emulator written in Go. It is
minimally functional (e.g., Super Mario Brothers and Zelda are playable) but
incomplete (e.g., missing audio, mappers, etc.).

What (mostly) works:
- CPU: official 6502 opcodes
- PPU: basic functionality
- Mappers: Nrom, Mmc1
- Input

Gomu relies on a local patch to Go-SDL that switches the event interface to use
polling. Without polling Go-SDL drops events on Windows
(https://github.com/0xe2-0x9a-0x9b/Go-SDL/issues/25).