Besides the walls (which are supposed to delete themselves so you can progress), how often did you notice the actual alien entities despawning or deleting themselves during your playthrough?
Just to clarify: the enemy deletion isn't a bug—it's actually my fix for the performance issues! Without it, the frame rate was tanking down to nearly 0 FPS (though on Level 5 it drops to around a minimum of 20 FPS).
I had the despawn distance set way too far before, so right now enemies despawn at 3,000 pixels to keep the game playable. I might bump that up to 5,000 pixels later after some more optimization. Thanks for the feedback!
