My biggest issue here is the projectiles being spawned at random, especially how they're used near the end of the game.
I'm being punished for moving more than 2 seconds, but I also need to be constantly moving in order to avoid the enemy chasing me and projectiles falling from the sky. I had to pause for a moment to recharge my timer, then all of a sudden a projectile falls on me. I think this is just a weird way to make your game hard for the sake of it being hard, and you should try avoiding that.