Within each level, the player may collect power-ups that enhance the ship's weaponry. Weapons are categorized into two different types: primary weapons and secondary weapons. Primary weapons range from a variety of laser weapons to the Plasma Cannon and the Vulcan Cannon, while secondary weapons include different types of missiles and mines. Most primary weapons consume energy at different rates, but some, such as the Vulcan Cannon, use physical ammunition instead. In contrast, each secondary weapon has its own quantity. The player can also collect equipment items which grant special abilities. For example, the Quad Laser modifies the laser weapons to fire four shots at once instead of the standard two, while the Afterburner allows the player to temporarily fly forward much faster than normal. Additionally, many stages have human hostages that give an additional point bonus if they are rescued before completing the level. Shooting out certain control panels causes a variety of events, such as doors opening, walls being removed, or force fields being deactivated.