I spent more time than I want to admit on your game :)
It reminds of me the zombie mode in Call Of Duty ... gives me so many good memories :)
However, as others said, the spawn rate is a bit too much at the beginning, so hard to get past that. I also get stuck a lot against the walls.
Finally i wished it was more clear what arrow we have next and the current (like maybe in tetris where we see the next and current blocks) so we can strategize more and maybe see more of the effect in game, because honestly i can"t remember the text you wrote on Itch when I play :D
But I spent a really good time on it :)