Commander Keen

Commander Keen (real name: Billy Blaze) is a character from a series of eponymous platform games by id Software. An incarnation of the character can be found in the super-secret Doom II map, Level 32: Grosse, as an easter egg. In the final room of that level four hanged Commander Keen bodies are suspended from ropes by their necks around a metal cube containing the exit switch. The player must destroy the four hanged Keens to trigger the door that hides the switch.

When killed, a Commander Keen emits an electronically-distorted death cry as he falls off his hanging rope to the ground, his eyes wide open facing the player with a horrified look, middle body torn apart showing bloodied organs and ribcages, but his head and blood-soaked tennis shoes are clearly left intact. The horrified face Keen displays when killed is the one you see on Billy when he flies out of the level upon losing a life in the original Commander Keen games.

The Commander Keen can be considered a monster in the technical sense as he counts towards the kills percentage, will respawn under the corresponding settings, and is not included when the -nomonsters parameter is used. He does not, however, pose any threat to the player as the true monsters do.

Technical
Internally "KEEN" is used as a prefix for sprites relating to Commander Keen. The type of the object inside the source code is given the name "MT_KEEN". The sounds "DSKEENPN" and "DSKEENDT" are used when the Keens are injured and killed, respectively. When all the Keens in a map are killed, any sectors tagged 666 will open as doors.

Appearance statistics
The IWADs contain the following numbers of hanged Commander Keens: