: Open the file in an emulator to verify that your code changes (if you are modding) worked correctly.

In the world of Sega Genesis homebrew and ROM hacking , this file is often the main source file that developers use to compile a playable ROM. It contains the "brain" of the game—the logic for Sonic’s physics, enemy AI, and level transitions. Sega Genesis/Mega Drive. Language: Motorola 68000 Assembly.