In the game hold <Alt/2> [ENTER] then press:
<F10/D>= Record a demo
<F10/E>= Restart game
<F10/G>= God mode
<F10/I>= Free items
<F10/J>= High jump
<F10/M>= Memory usage info
<F10/N>= No clipping
<F10/T>= Sprite test
<F10/V>= Add VLB
<F10/W>= Jump level
<F10/Y>= Shows secret passages, but makes the game look weird
Go to the Pyramid of the Crescent Moon, stand on one of the two crescent moons on the floor, and Keen will "moon" you. You can only do this once.
<ctrl-cursor> Makes you climb poles and swim faster
<END> Saves all the Gnosticenes and gos to the end of the story.
<BAT> Gives you 99 shots and 1 up.
First village, under houses in tunnel by lava pool, there's a hidden gap that you can reveal with <F10/Y>, and jump through with <F10/J>, which leads to 9 extra lives.
To get to the pyramid of the Forbidden: In the pyramid of the Crescent Moon, go to the bottom and gather all of the inch worms at your feet. When the inch worms are gathered, they will form a foot. Jump on the foot and it will fly you to the pyramid of the forbidden.
You can not get to the raindrops or lifewater flasks floating over the underground river in Lifewater Oasis. It's a teaser, don't waste your time.