How does your submission match the theme?
You only have two abilities, both of which influence the game in multiple ways. Your main action is to fire a stream of lava, which destroys enemies and turns them into health/ammo pickups. The lava can also be used to weld (i.e. heal) either of two rival battle stations and to destroy incoming debris. After a few seconds however, the lava cools off and becomes the aforementioned debris. Using the secondary ability, an area of effect magnet, consumes a larger amount of ammo and allows you to salvage the cold lava to regain lost ammunition, as well as score points and additional ammo for pickups from destroyed enemies. The magnet can also be used to instantly cool off lava, turning it into debris that can block enemy laser fire (but then moves on to endanger the player)
If the player stocks up on too much ammo, they overheat and start taking damage. The magnet can also be used to spend ammo quickly and prevent overheating.

Third-party resources
The game was created in Game Maker Studio 1.4 Professional

Contributors
The opening screen and the music where created by my wife Danielle Nobbe a.k.a. callmecrashy