Boss seems waaaay too tanky. I slipped off the platform when it was at about half health and don't really want to try it again as it already took what felt like forever to get to that point. Dunno if I'll come back to this to finish it out properly, I'd like to see the other weapons but I don't really want to do that boss.
Up until that point I was having fun, though - this is a pretty solid little fps. The movement and shooting were simple but all felt plenty fluid and engaging. I did experience a bit of stuttering but that might just be typical web build lag. I do agree with the comment on the page that moving the platforms around would probably make more sense to be bound to WASD, since you can't move the player while doing that anyway - would save having to move my hand over to the arrow keys. I also thought the glitch effect as a damage indicator was neat in concept, but in practice I found it really hard to distinguish how much health I had, and even harder to tell when I'd just gotten hurt - I think some extra indicator at the moment you're hit might help.
I don't have a lot to say about the visuals, they're alright. Polished enough that they caught my eye from the submissions page. The sound design is really good, the shooting sounds are nice and satisfying. Music is a bit of an unusual choice but it did end up working! Good job making that fit.
Dunno how I feel about the theming, interpretation is a tad trite and from the one upgrade I got it didn't seem like the side effects had much of anything to do with the ability itself. I guess it's possible they get more interesting from there, but I wasn't especially feeling the "absurd" part from that one :P I'm giving the benefit of the doubt for my rating in that category for now though, since there's clearly a meaningful effort to incorporate the theme.