Knuckles' Chaotix is a 1995 side-scrolling platform game developed and published by Sega for the 32X. A spin-off of the Sonic the Hedgehog series, the game features Knuckles the Echidna and four other characters known as the Chaotix. The story follows the team in their efforts to prevent Doctor Robotnik and Metal Sonic from obtaining six magic rings and conquering a mysterious island. Gameplay is similar to earlier Sonic games: players complete levels while collecting rings and defeating enemies. Knuckles' Chaotix introduces a partner system whereby the player is connected to another character via a tether. This tether behaves like a rubber band and must be handled appropriately to maneuver the characters through the stages.
Unlike many other Sonic games, Knuckles' Chaotix was not developed by Sonic Team, but another internal development team at Sega. Development can be traced back to Sonic Crackers, a 1994 prototype for the Sega Genesis which experimented with the tethering mechanics and featured Sonic and Tails. The concept was retained when development transitioned to the 32X under the working title Knuckles' Ringstar. Sonic and Tails were removed from the game and replaced by Knuckles and four other characters, including Mighty the Armadillo, who first appeared in the arcade game SegaSonic the Hedgehog (1993).
Critical reception to Knuckles' Chaotix has been mixed. Critics found the tethering physics cumbersome, although some appreciated it as an attempt by Sega to innovate in the series. It is seen as the last in the "classic" 2D style of Sonic games before the series moved to 3D. Some characters and concepts introduced in the game were featured in later Sonic games and media. Despite interest from fans, it has not been re-released beyond a brief period through GameTap in the mid-2000s.