Developer: Gravity Box Studio
Platforms: Windows, Mac, Linux
Price: $3.99 (Desura)
In their own words, Gravity Box's Studio's Inverto is a "first person shooter-puzzler with gravity manipulation." There are no enemies, it's just you, your gravity-switching gun, and levels where up, down, left, right mean nothing. If you're up for some challenging spatial puzzles, then you'll be interested in Inverto.
article, the developer discussed what will be coming in future updates, including more guns, more exploration, elements like timed gravity fields and gravity zones, and more. I've greatly enjoyed my time with Inverto and look forward to seeing how it expands and evolves. If you're interested, there is an early alpha demo available on the game's site and if you'd like to see the game on Steam, Inverto is also on Greenlight.