Commander Keen 1-6 PC cheats

Commander Keen 1-3:
To enable cheat mode, press ALT-2-ENTER during gameplay.
Now press F10, and any cheat key:

G - God mode
W - Jump level
J - High jump
N - No clipping
I - Free items
T - Sprite test
D - Record a demo
V - Add a VLB
M - Get memory usage info
E - Restart game
S - Put game in slow-mo
Y - Makes the game look wiered
C - Mega-stats

Press C+T+SPACE to recieve the pogo stick, all the key cards, and
a lot of ray gun charges.

While at the map level, press SHIFT and TAB to bypass a city.

Commander Keen 4:
Press B+A+T to enter cheat mode

B - Set border color (1-15)
C - Number of active/inactive objects in the level
D - Record a demo
E - End or finish the current level
G - God mode (you can't die)
I - Free items (add 3000 points and 99 shots)
J - Jump mode (you can fly anywhere)
M - Memory usage display
N - No clipping (fall through ground)
S - Slow motion
T - Sprite test display
V - Add 0-8 VBLs
W - Warp to any level
Y - Reveal hidden areas (shown in normal color)

Commander Keen 6:
F10-E - End level
F10-G - Invulnerability
F10-I - 99 ammo, all keys and items
F10-J - press and mouse and you can fly
- - no clipping, but you die, if you leave the level
F10-W - Warp to any level
F10-Z - Background turns grey and all secret ways will be visible
F10-D - Records a demo, pressing + again will save the demo.