It was really hard to learn. I really try to go to the top but I gave up. The best strategy that work for me was shooting like crazy to the other side I wanted to go but that only cause to lose my health with the enemies. (I suppose that's intentional)
I tried the grapple and I think I was starting to get the trick, but my motor control doesn't help. My critic was that the grapple has the same aim at where you shoot, so for me I have to try and shoot and grapple in the other direction. If that was intentional then it was really hard for me.
On the good side I liked the color palette and the idea is cool. Good work!