Birdman is a one-level technical demo of a Keen 4 mod. It was the first mod released for Keen 4. It is unique in that it changes the gameplay rather than changing all the graphics like most mods. The player is no longer Commander Keen, but a flying Blue Bird. On a technical level, it puts the player into "swim mode" (as used in Well of Wishes) to make it seem like the player is flying. The Schoolfish has been replaced by a small bird to provide the level with more flying creatures.