Commander Keen

Commander Keen is a character named Billy Blaze 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 if you die in the original commander keen games.

The Commander Keen can be considered a monster in the technical sense as it counts towards the kills percentage, will respawn under the corresponding settings, and is not included when the -nomonsters parameter is used. It 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 Keen objects 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: