nice. I like how the enemy can hide underneath the spawner things it makes them seem smarter like they got 2 states: 1 chase you down out in the open, and 2 stay still hiding under cover so you can't see exactly where they are making hitting them a little bit more challenging and getting shot at by them more surprising -> increases fun
I do have some remarks however:
see this light grey patch? this is a blocker, you crash into it. so it is like a wall or a concrete barricade or something. but look at the sides of the arena, they kind of have a LoZ ALttP type slant to them, so then this middle thing should have that too, right? like the sides of the walls should "pyramid" out around it a little bit, so so that you know it has height. otherwise it just looks like a symbol painted on the tarmac that you shouldn't hit into it.
next up: you need to put a super wide black rectangle behind the game scene so that on ultra wide monitors the out of bounds area is just dark, instead here you can see that to the left (and it is the same again on the right edge) there is different hues of grey and even an out of bounds slab all visible. cover it up with a black rectangular
And lastly, the movement feels like it gets stuck too much. It IS capable of sliding as if I D (right movement) into an angled surface, I slide up it.
But it'd be good if holding W (up movement) into the top wall caused on collision some kind of slide, not sure how to choose the left or right, maybe the side of the screen half your mouse is on?
BUT FAR MORE IMPORTANTLY, if I hold W+A or W+D (up+left or up+right) into the top wall, I'm still stuck? just because diagonal up still collides with the wall doesn't mean I should be stuck. If my W up is stuck, but my D right is not stuck, then W+D up into the ceiling should behave the same as just a D, I move to the right sliding along the ceiling.
As it is, you can hold W up to the ceiling, let go, then hold D to go right, and pause yourself momentarily along that by holding and releasing again W. In this case, holding or releasing W should have no effect. Unless you are going to turn it into a side scrolling platformer and have wall cling / wall jump mechanics or something.
I think if you just in the collision handler, see if two directions are held, if so, then see if you'd still collide if only the first one was held, and again if only the second one was held, and then act like that case, would solve 90% of the sticky movement problem on the game feel.