Commander Keen Series

Chat Codes:
-----------
-- Mild cheats:
 [C]+[T]+[Spacebar] : Free items
 [F8]               : Some funny stuff.
 [G]+[O]+[D]        : God Mode
 [Shift]+[Tab]      : End level

-- Hard cheats:
Add to the commandline (for series 1-4):
NOWAIT
(This also removes various delays and nagscreens)

Then, in the game, use [F10]+ some letter keys :
[W] Warp to level        [E] Restart
[T] Sprite test          [Y] Mess up sprites
[I] Free items           [S] Toggle slow motion
[D] Record demo          [G] Toggle God mode
[J] Toggle jump cheat    [C] Stats
[V] Add VLB's            [N] Toggle clipping
[M] Memory usage

You may also try adding TEDLEVEL, COMP, NOCOMP.

-- Secrets:
Episode 4:
In the "Pyramide of moons" get the  yellow gem and 
open the door then get all of the 12 worms in one 
place and they will turn into 
a foot climb the foot and enter the secret level.