>"On Dec. 14, 1990, Apogee Software released Commander Keen: Invasion of the Vorticons. It was the first in a series of PC shareware games that brought fluid, Mario-like platforming to the PC. It also launched legendary developer id Software. Here’s why it was special."

The first Commander Keen game, Invasion of the Vorticons, is split into three episodes designed for PCs with MS-DOS. In the first episode, you play as Billy Blaze (aka Commander Keen), a kid who must travel to Mars to repel an invasion of dog-like aliens called Vorticons.

>"On Dec. 14, 1990, Apogee Software released Commander Keen: Invasion of the Vorticons. It was the first in a series of PC shareware games that brought fluid, Mario-like platforming to the PC. It also launched legendary developer id Software. Here’s why it was special."