Oh man this takes me back. I found the first Commander Keen game on a discount sale at a computer shop when my family was on a vacation (this was several years after it was released). I picked it up because the crappy older PC my family had was just powerful enough to run it. I loved that game! I actually ended up owning all seven of the PC versions and beat them all up and down. Something about the tongue in cheek humor and alien level design really appealed to me.