The Keencyclopedia
These one-eyed green aliens are one of the main inhabitants of Mars. These martians are extrememly friendly and won't hurt you at all. But they do have a certain tendancy to push Keen into acid, or a pit so make sure you watch out! If you want to be merciful, just jump on the Yorp to paralyze it for a bit, or you can always do it in forever with one blast from your raygun. At one point in history, the Yorps were slaves to the Gargs, until the Viking Spacecraft landed on the Despot Garg, killing it and freeing the Yorps.
Found in: Keen 1