I like the idea of attacking causing you to lose health. I tried to make a game like that in the past, which didn't end up being very fun, but you've mitigated some of the issues with health pickups, so it plays a lot better.
I unfortunately couldn't get very far, because in the second map, the game just grinds to a halt on my PC. I don't know if it's because there are a lot of CPU intensive things going on or something else, but it gets worse over time, so maybe some kind of memory leak?
Also, I like the colourlessness of the environment, though some more contrast between the walls and the floor would have been good. It took me a while to realise that you can walk over the blocks with the lines.
Overall, from what I saw, it looks like a fun idea. Well done!