What's the difference between different roms? : r/PokemonROMhacks

: Ensure your file matches the name 1636 - Pokemon Fire Red (U)(Squirrels).gba .

: Advanced hacks that change game mechanics (like adding Mega Evolutions or the Fairy type) require the specific memory offsets found only in the 1.0 version. If you are trying to play a hack like Radical Red