Commander Keen Episode One Secrets

Commander Keen Episode One is a very basic game. Because of this, there is only one glitch.

If you hold down the keys C, T, and SPACE BAR, then you will get lots of ray gun charges, a pogo, and all of the keycards.
If you down the keys G, O, and D, then will become invincible and be able to fly with your pogo. You will also be able to walk through walls on the map level.
On the map level, hold down the keys SHIFT and TAB to walk through a level.
If you touch the top of a level, Keen will shake.
To get to the secret level, you must enter the level that is like a giant red maze full of lots of Gargs. Go to the bottom of the red maze, by a hole. Drop down the hole, but look out for the fire at the bottom. Go right, and jump on the invisible block(you can see nothing but its upper left corner). Jump over the wall and then get shot by the ice cannon correctly so that you fly over the next wall. Once the ice breaks, go in the teleporter. You will now be on the map level. The secret level is right in front of you.
In the level with the vacuum cleaner ( level 16 ) , you can kill the final Vorticon with about 100 shots. I don't know why anyone would want to do this though.

That's all I know. If you know of another one, e-mail me.