Void Slayer is now available for on Steam, offering a rapid-fire arena shooter where the twist is the arena itself is your health. This is also available as part of the Void Slayer Bundle which also includes SUCCUBUS. A quick look at gameplay can be found in the Launch Trailer. Here's a fuller explanation:

Void Slayer is a unique arena shooter where each hit taken will claim some of your fighting space. Avoid it with the help of double jump and dash. Dispose of your enemies by using two different attacks - one for each hand. Keep your eye on nightmarish obelisk structures - they serve as passageway for your foes. Destroying them will not only close the portal, but also reward you with powerful gems which will upgrade your attacks. Survive as long as you can and compare your scores with other players - find out, who is the true Void Slayer

Nameless Gods stripped you of your mortality. Your unyielding soul was cast into the void, and only thanks to your immense will, you suspended yourself above it. But the fight has only begun. Hordes of misshapen creatures will try to knock you down into the mindless abyss. How long will you survive?