Battlestorm

The game takes place above the surface of a ruined, devastated planet: each level starts within a large area, in which your ship has free movement. Avoiding surface hazards, such as auto-aiming turrets, the goal is to destroy enemy spacecraft that hover around the large area in groups. Each wave of attacks is followed by a bomb-dropping mothership, which you must hurry up and destroy before it moves off the playfield, in order to proceed to the next wave; the last mothership gives way to the boss - a gigantic spacecraft that will chase you around the playfield. Beaten it? you are transported to a short section of standard shooter fare, where the screen auto-scrolls vertically, at the end of which you face a final monstrosity. This ends the level - on to the next one. Absorbing enemy fire will deplete your power, while collecting power-ups and destroying turrets can bring it back up somewhat. At 0% power, the game is over - although you may get an option to continue, based on how far you got.