To enter cheat mode
Press A + 2 + [Enter] during game play to enable cheat mode in Commander Keen 4 or 5. Press [F10] and one of the following keys to activate the corresponding cheat function. Note: You will lose a life if you leave the level with the "No clipping" code enabled. Activate the "Record demo" code again to save the demo.

Key Effect
G God mode
W Level select
J Flying jump
N No clipping1
I 99 ammo, 3000 points
T Sprite test1
D Record demo1
V Add 0-8 VLBs1
M Display memory usage1
E Level skip1
S Slow motion mode
Y Show hidden areas1
B Set border color 1-151
C Show active and inactive object numbers in level1

Fly in Commander Keen 6
Find a spot where you want to go up, and jump. While in midair, shoot down as you are falling. . If done correctly, Keen will be standing about a one shot width off the ground. Just look up and shoot. You will take off straight up at the speed of your shot. Note: Some practice is required to get the correct timing

Items
Press B + A + T to receive an extra life, 99 rounds of ammunition, and all four diamond keys for a level. This has no effect in Commander Keen: Dreams