Commander Keen is a series of side-scrolling platform video games developed primarily by id Software. The series consists of six main episodes. Game were originally released for MS-DOS in 1990 and 1991.

All of the games in the Commander Keen series are side-scrolling platform video games: the majority of the game features the player-controlled Commander Keen viewed from the side while moving on a two-dimensional plane.

he levels are composed of platforms on which Keen can stand, and some platforms allow Keen to jump up through them from below.

The episodes all contain a different set of enemies in their levels, which the player must kill, stun, or avoid. These enemies are typically aliens or robots. Levels can also include hazards, such as electricity or spikes.