The challenge level is great! Don't change a thing please. Its fun to take advantage of seemingly unintended attributes of the game. Its not very difficult if you figure out the seemingly unintended attributes. ;)
Tips for challenge level: If you fall off a block (not jump) then you can jump in mid air. There exists a point in time when a laser can touch you and not kill you while you are able to jump, if you jump immediately then you can ignore that laser (you can't touch the gun though because that will kill you and you can fall through lasers). You probably know this, but lasers don't go through enemy bodies.
I would appreciate being able to save the game at the beginning of a new stage, and so no one exploits it maybe the save file could be automatically corrupted if the person makes a move and then at the beginning of the next stage you could make a new save or if that exact way isn't possible maybe something else that uses the same concept. It would be nice.
Here I was trying to calculate all the possibilities with my splash upgrades and losing all the time on the final floor; and then I read the comments about how the shield upgrades are the way to go... let me tell you what, the shield and lighting upgrades are the way to go! Unless you wanna spend 10s of minutes worth of time calculating all the possibilities. I won the first time I targeted the shield upgrades over the splash upgrades.
It would be nice to have some way of recording progress and seeing how much longer until the possible endings (I am assuming there are multiply endings based off of the choices) can be reached.