Star Cannon: Invasion Formation is a 3D shooter in which you have to protect three separate cities from being destroyed by a hostile alien invasion. This involves shooting at them with any of your three weapons accessible using the keys 1, 2 and 3. Enemy locations are always marked by a red squad icon placed above the troops or ships, making them easier to spot on screen and disappearing only after all units in that squadron have been dispensed with.

Holding down the left mouse button fires whatever weapon you have currently selected. Cities, ammunition and shields also automatically regenerate when not being depleted by one cause or another. This TIGSource Cockpit compo build does have a couple of problems (for example randomly crashing back to the desktop after several minutes of play), but the developers have promised to look into these issues and will hopefully resolve them sometime soon. (unzip instructions, gameplay video)