great game
great concept i like it alot and i know that you probably would have add more stuff if you had the time for it but i just want to give some recommandation which i think would make the game better.
when you enter a level give us a preview how the enemies move. mostly you come into a level and just give it a lucky try hoping for the best because you dont know whats actually going on.
also like others said give us a general restart button and make your timeline thing , dunno what to call it, more editable or somethin like showing us the "ghost" of our previous try.
and one personal thing is every time you shoot you could make a short slowmo, it would make it way more spectacular and satisfying if you get a right shot ;)
im really hoping for a sequel.