Knuckles' Chaotix is one of the few Sonic games that doesn't feature Sonic himself. The story differs between the English and Japanese versions of the instruction manual that came with the game, but they both involve Dr. Robotnik trapping Knuckles' friends on a special island. Knuckles must now save his friends and discover the mystery behind the island. The gameplay is similar to that of earlier Sonic games, with the added gimmick of being bound to a partner with an elastic tether, giving the game its reputation for wonky rubber band physics. After each stage, the next level and your next partner are selected via roulette.