All structures repair themselves to 50% life. All structure fires are automatically put out.
This all-in-one safety system automatically dispatches robotic drones to put out any fires and perform basic repairs on damaged structures. Although these drones are effective at doing basic repairs, they do not have a strong enough AI to perform the more delicate repairs needed to restore a structure past half life.
The following section contains information from a previous version of StarCraft II which is no longer valid.
The fusion core experienced a rather rushed and unplanned development. It was the intention of the designers that advanced terran structures feature circular shapes, but the fusion core's shape became simple and repetitive. The front and back pistons were tweaked to oval shapes to make them more interesting.
Players used to have a choice between three abilities on each battlecruiser. This was removed from multiplayer by the beta, but is featured in the campaign.
A battlecruiser will have the choice of being upgraded with either the Yamato Cannon, the Missile Barrage attack, or the Defensive Matrix, but cannot have more than one. Once one has been chosen, the battlecruiser may not switch. The upgrades are made individually (by selecting the battlecruiser). Upgrading the battlecruiser is very quick.