Commander Keen 1 - Gameplay
Commander Keen is a series of Jump&Run/Platformer games made by Id Software and published by Apogee. Commander Keen 1 came out in 1990
The game is shareware and that means you can download episode 1 for free. (Just search for it on google)
The first Keen game of the 7 that are out there (Yes 7 not 6 Keen Dreams is also there ;) )