Rats! (known as Reservoir Rat in the EU/UK) is a platform game developed by Tarantula Studios and published by Take-Two Interactive Software for the Game Boy Color.
Rats! is a 2D platforming game in which players try and collect a set amount of food that is scattered throughout each stage. Once the number of food items has been hit, the player can locate the exit and go through it to move on to the next. The food must be collected within a time limit or a life will be lost.
There are five "worlds" in the game, each containing 15 individual stages. There are enemies such as snails and foxes that must be avoided or shot. There are also various objects in the stages that can hurt the player such as bouncing tomahawks.
The game contains a password save system allowing players to continue where the game was left off by inputting the correct level password.