Mmh there's some potential but for me it doesn't really play well.
First of all having a web build is nice and all but the huge margins and the lack of fullscreen option is not a great start, had to put my browser at 230% zoom to get a decent size, but well that's a minor issue.
The enemies attacking from far offscreen is quite unfair, oftenly running into bullets that just suddenly come in screen from nowhere. I'd prefer a slightly more zoomed out view or closer range combat, fighting enemies you can't see isn't much practical.
Apart from that I feel like only the machine gun is suitable, the shotgun does some damage but with its spread it's only viable if you have a lot of enemies, and even then the damage is still low, the sniper fires so slowly you can't even kill the enemies faster than they spawn, and the pistol is ok for a few enemies but you quickly get overwhelmed.
The enemies having friendly fire is nice, though that also means a good strategy is to run around the border of the map while enemies group up and shoot themselves, not the most fun way to play though.
About running around, the enemies spawning on your trajectory is quite annoying, it's not just every once in a while it's like, you start moving and a few seconds later you suddenly run into an enemy, turn around and boom another one, and again, and you quickly end up surrounded which then becomes hell to dodge everything.