Really cool mechanic and a fun execution, the time slow really let you think out what you wanted to do with your shot and perfectly execute it making a good plan really feel under your control!
I'm not sure if this problem was for everyone, but the ground layer tiles flickered a lot when moving vertically causing some pretty bit discomfort. Also perhaps giving the enemies some sort of red flash and hit reaction ( with a bit of a slide away from the impact for the juiciness ) would help a lot in readability. Also if you wanted to carry this farther into a larger scale game, then perhaps adding visual health indicators ( growing cracks and the likes ) then this game would read really well and help the player make quicker split second decisions :)
I really enjoyed playing this game and would love to see you carry it on a little more, good job!