Commander Keen is a series of platform video games developed by id Software in the early 1990s. The games follow the adventures of a young boy genius named Billy Blaze, who travels through space as the titular character, Commander Keen. Players navigate various levels, solving puzzles and defeating enemies while collecting items. The original game, Commander Keen in Invasion of the Vorticons, was released in 1990 and became popular for its innovative gameplay and colorful graphics. The series is notable for its use of shareware distribution, which helped popularize the PC gaming market during that era.