Great fun to play! However, I would like to mention a few bugs and oddities:
Oddities:
1: If you die close to your spawnpoint, you get extra time before the enemies move.
2: The walls' collision is way rougher than that of the enemies.
3: The enemies don't have a speed limit. They probably should.
Glitches:
1: When splitting, enemies can get trapped inside other enemies. This leads to erratic movement that is actually quite fun to play against. Rarely, these enemies are so similar in size that they forcefully eject each other at lightspeed. <Personally, I would be delighted to have a mode where one fights against these, or even possibly a fight editor that allows these.>
2: Alternatively, when splitting, enemies can interlock. This usually leads to them forcefully ejecting each other at lightspeed across the arena.
3: Another thing that can happen when splitting is a red ring either disappearing immediately or flying off the screen, causing the enemy to remain both oddly shaped and invincible.
4: Sometimes, the bullet will go directly through the enemies without damaging them. This happened way too many times.
5: If your bullet is too close to the wall when you leftclick, you may find yourself blue for a very long time. Every time I encountered this glitch, I managed to escape. Once I won a stage using this glitch.