This game has multiple problems.
Why can't we use the arrow keys? Are they even used for anything?
Because you made levels yourself instead of generating them, like "No Summit", they're very repetitive and they're really short.
No music in the game? A simple Bosca Ceoil track would've been no problem.
What do the cat powerups do? They don't seem to serve a purpose.
There's no difficulty curve. I rarely found myself dying and I don't think the difficulty ramped up during the short-lived levels.
The art is pretty good. Though I do wish there were more animations for the enemies. The enemies are also the only ones with... three colours? While every other sprite in the game has two.
Anyways, I just don't recommend making the levels yourself, since that doesn't add much replay value. Other than those gripes, this game is pretty decent! I'd love to see what you come up with next.