When you finally check your party menu to see Subject 1636, the sprite has grown to fill the entire screen. It isn’t a squirrel anymore. It’s a mass of twitching limbs and stolen Pokémon parts. The "Close" button is gone. The only way out is to turn off the console.
The ROM refers to a specific, widely used digital dump of Pokémon FireRed (v1.0). While it is fundamentally the same game released in 2004, this specific "Squirrels" dump is a staple in the Pokémon ROM hacking community because it is considered a "clean" v1.0 base. Key Characteristics of the Squirrels ROM 1636 pokemon fire red usquirrels rom free