reviving this thread...
so I dont know if you heard about the shoot through the roof bug. basicly its done this way
Keen's pogo and jump sprites have slightly different hitbox heights; therefore, if Keen jumps until just before he hits a ceiling, then pogoes, he will occasionally shoot right through the ceiling on top of it. This only works for ceilings one tile thick. (Though it can be seen with all other ceilings, Keen just will not go through the second row of tiles.) This is easier with God mode, but is still difficult to do.
Steps to reproduce:
* Enable God mode
* Jump somewhere you'll hit the roof
* Press pogo right before you hit the roof, it helps to be moving forward
As seen here
Well as you can see it SHOULD be possible to do without godmode on but I wasnt able to do so. However, with god mode enabled its a piece of cake. Here is a video demonstration of what it looks like
Link to video
Would be really great if we managed to pull that off