itch.io

Even on my PC it gets slowdowns if you can survive long enough, but the main performance bottleneck is enemy-to-enemy collisions (where enemies are moved outside each other so you don't end up with a single 'conga line' blob) so you could get around that by focusing more on fewer stronger enemies instead of tons of weak enemies, or maybe change things around so each individual enemy object only collides with that one object, rather than the parent_enemy colliding with parent_enemy, so individual hordes keep their shape but they just phase through other groups.