Here is a helpful blog-post style guide regarding this specific ROM, including why it is popular, its technical details, and how to use it safely.

Even though the actual Game Boy Advance hardware is over 20 years old, this specific file remains one of the most sought-after resources for fans who want to play modern versions of Kanto with updated graphics, Mega Evolutions, and new Pokémon. Difference between FireRed v1.0 and v1.1 Saves? 28 Aug 2017 —

Here’s a review of Pokémon FireRed Version (2004) — specifically the ROM revision often labeled with 1636 and -u--squirrels- (likely a scene release naming convention).

If you are getting into GBA emulation or Pokémon ROM hacking, you have likely encountered the filename 1636 - Pokemon Fire Red (U)(Squirrels).gba . Here is everything you need to know about this specific file.

The "Squirrels" ROM is the most widely used base for creating and playing massive Pokémon fan games, such as and Pokémon Unbound . Its popularity stems from its status as a "clean" dump of Version 1.0 of the original 2004 Game Boy Advance release.

: Unlike version 1.1, the 1.0 (v1.0) version is the only one compatible with major ROM hacks like Pokémon Unbound , Radical Red , and Pokémon Clover .