The later waves were becoming almost impossible, so today was all about powerups.Destroyed enemies

now have a 10% chance to drop one. There are three types: a shield that rotates around the player, rapid fire that reduces the weapon cooldown, and a wide shot that fires three bullets at once.

Each effect lasts for a limited amount of time, so I also added small HUD indicators showing which power-ups are active and how much time they have left.