The game features ten stages plus and endless mode and a tutorial; content can be expanded by using the simple level editor. Each level offers freeform placement of structures: resource collectors, power generators, turrets, walls, research buildings, and repair facilities. Spare resources can be used to upgrade existing buildings, and the simple AI can be funneled by clever use of walls. Your ship can directly fire on enemies using awkward ship controls with imprecise aiming; a “ghost” movement mode is provided to navigate through walls. Overall, SBX: Invasion is an enjoyable entry in the tower defense genre thanks to unrestricted building placement and the level editor.