Because the "Squirrels" dump is the most pristine, unedited copy of Fire Red Version 1.0, developers build their hacks directly on top of its exact memory hex code. If a player tries to use a different base file, the patching program will inject custom assets into the wrong hex addresses, creating immediate graphical glitches, audio bugs, or game-breaking crashes. Feature / Identifier Verification Metric 1636 - Pokemon Fire Red (U)(Squirrels).gba CRC32 Hex Code DD88761C File Size 16.0 MB (Unzipped) / ~5.1 MB (Zipped) Software Target Pokémon Fire Red Version 1.0 (USA) Popular ROM Hacks Requiring the 1636 Base
: A completely new story and region with modern quality-of-life features.
This refers to the scene release number from the group "Squirrels," a trusted group that dumped the North American (U) version of the game.