I think I like the idea of this game more than this iteration of it.
I like the idea of shooting your way through the level, making your own path, but I found that it was more reliable to not shoot at all, and keeping the walls for cover or for wall jumping. If there were more of a reason to explore the level horizontally, I'd shoot more, but as is, the health or rockets from the chests weren't enough incentive.
I generally liked the movement. The tumble jump in particular felt pretty good, and I like the sections in the autoscrolling level encouraging you to use it. The wall jumping didn't feel as good though, particularly with how I slid up the wall unpredictably. I suspect it might be a bug with wall jumps on a tile boundary.
I managed to get to the boss a few times, but I gave up when I saw I would need to jump on it 6 times after using the 2 rockets you start with.
There is a good core of a game here, and if you plan on continuing development on it, I would be happy to check out any updates.