Mission 0

This secret mission is accessed by looking at a mission summary screen and then changing to Mission 0 by using the up or down keys (W and A by default).

The challenging part of this mission is that there are no walls, ceiling or floor. It is easy to fall to your death. To beat this mission you must destroy everything in it.

Tips:

Save your blue force generator until there is nothing to stand on. It will make it easier to survive until everything is dead.

Use the Graviton Turret or Death Blossom to stand on by using their jets. You can turn them on and off to stay fairly level and this is the only permanent place for you to stand.

Jump off of enemies when there are no more spawners.

Sufficiently upgrading the Blaster Recoil Upgrade can allow you to effectively fly by shooting downwards. This is easy mode for this level.

After destroying all the spawners a second group of spawners will appear after a period of time. Destroy them and all the enemies and you win the level and get Infinite Fuel.