Did you know that level 1 contains a short cut to the exit?
Notice that when you go out of the teleport that requires a yellow key, you have 400 credits to your name. When you go upwards in the area you teleport to, there's an armor ball and a pick axe waiting for you. Collect 200 more credits and buy both.
Then head down to where you emerged with the yellow-key teleport and you'll notice there's a crumbly wall. Equip the pick axe, then start ramming here with the mouse button held down. You'll break through, then ram through the second crumbly wall on the other side of the chasm. You're at the exit.
Note, that you must be very quick to collect the additional credits, else the armor ball + pick axe disappear from the playing field.