Amazing work, you really nail the brief with this one haha, it's loads of fun and the sprites and animations are super cute and the whole thing just works on every level. If I'm trying to find some constructive criticism I'd say you could expand the theme to be more wacky and in tune with the crazy vibe of the whole genre, so maybe make the power ups more original, even if they do the same thing. Like, even if the shoot faster add on makes him shoot faster, it could just be called something entirely different, I dunno, he could be shooting peas so it could be the Pea Shooter Plus or something, with a cute Pea with a face bouncing up and down instead of the Sergeant stripes haha - that's a super bad example I know, I just thought of it off the top of my head :'D
Anyway just thought I'd try and bring something to the table that might help make this incredibly awesome little game even better if you take it on, because basically you've done an amazing job with this as it is ;)