Originally conceived as an April Fool's parody, Dark Void Zero is a spin off of Airtight Games' original Dark Void. The earth is threatened by an alien race that plans to control human life. The aliens are called the Watchers and come from the Void, a place between worlds. Before, unstable portals have saved earth from an invasion but now the watchers have managed to build a stable portal. The only hope left now is a group of humans inside the Void who led by the great scientist Nikola Tesla battles against the invaders. The player takes the role of Rusty, the first human to be born in the Void. He is assigned by Tesla to infiltrate enemy territory and shut down the portal leading to earth.
Dark Void Zero is a side scrolling platform shooter with NES inspired retro aesthetics. The game features three levels and each contains a portal control code. The mission for the player is to find all these so that the portal leading to earth can be shut down. The gameplay works like a classic platformer where the player has to jump between platforms while trying to shoot down the enemies that tries to make life hard for him.
Like in Dark Void, the player has from early on access to a jet pack which allows him to fly around and reach otherwise inaccessible places. This can turned on or off at any time by double tapping the jump button, although it will be disabled when it comes in contact with force fields. The player also has access to numerous weapons and pickups. Primary weapons include the machine gun like liberator and the shotgun like disintegrator as well as the less common teleforce lance which can shoot through walls. There is also secondary weapons that are automatically used when attacking. Weapons can be upgraded (although only for ten seconds) to double fire rate or to shoot in multiple directions. Other pickups include extra lives, tech points (collect 100 to get an extra life) and health packs.
The player will come across many locked doors that hinder him. Therefore it's necessary to find the right keycard to be able to move on. There are also some doors that can be destroyed by force if the right weapon is equipped. Additionally the player can search for journals from missing soldiers that can be found across the levels.