Really good implementation of enemy AI! The level variety and addition of power ups is awesome too.
Feedback for improvement: The level variety is really neat, but visually all look very similar. I think doing some simple palette swaps for the terrain on later levels could make it feel more varied and add a better sense of progress without too much work. There are also some visual issues, such as the player health overlapping the level (and where you start quite often) as well as the timers on the bombs being very hard to see (I didn't even notice they had timers until around level 9). Fixing the collision issues sliding along the level walls would really make it feel a lot more polished too.
All in all, a really cool game though. Had a blast playing it! XD