The Retrobooster Website is home to Retrobooster, "an upcoming 2.5D survival shooter and cave-flyer" that began as a hobby project before becoming a commercial game project. The game is expected next year for Windows and Linux, and is the subject of a current Steam Greenlight campaign. This page offers a playable demo for each platform, and word is this will be frequently updated as the project progresses. Here's a bit on gameplay:

Retrobooster lets you pilot a thrust ship across the galaxy, focusing on the thrill of flying just as much as blasting enemies. Some cave-flyers keep the flying slow or neuter the physics in some other way, but Retrobooster enhances its survival theme by keeping the flying fast and tense. This is accomplished with a combination of clever control laws and realistic physics. Retrobooster also sports colorful explosions and other effects produced by a custom particle engine. All of this produces an arcade experience with a balance of bullet hell mayhem, flying challenges, and delicious pyrotechnics.

The gameplay consists of skill-based flying and shooting, grabbing tokens to get power-ups and weapons, and figuring out how to get through each level. Beating a level can mean rescuing people, solving puzzles, or surviving speed-flying challenges. Replay value comes from multiple difficulty levels, the chance to play for high scores, and your constantly improving ship control skills.