Atmosphir is a software-based game building tool for PC and Mac users that lets users put together their own gaming levels. Like many consumer-facing game creators you're only limited by the tools that have been given to you. In this case the tools provided are split up into packages of "blocks" that are both interchangeable and feature simple gameplay devices like moving platforms, and various themed texture elements that let you build worlds with grass, dirt, and sand.
The builder actually reminders me a lot of Cubescape, a product I looked at back in May. In Atmosphir's case, it's simply a matter of stacking pixels together on top of one another in a 3D grid. The big difference is that you can jump into your creation and play test it. Depending on what game play goals you set up, it changes what's needed to successfully get through what you've created.
The only thing I'm concerned about with this product is that the demo did not make playing the game look like as much fun as building the levels. I'm willing to withhold judgment until I get my hands on it, but it seemed to be lacking a decent physics engine and the graphics looked akin to Super Mario 64--a console title that came out 12 years ago. That said, look at something like Line Rider; if you give people simple tools and a platform they're going to go nuts.
To aid in that discovery process users can submit their creations to a central pool where others can jump in and play their creations, with some of the best items rising to the top. Also neat is the option to grab someone else's level and pull it back in the editor to make tweaks.
The service is a TechCrunch50 finalist, and is currently open for sign-ups, with plans to release a public client later this year. I've embedded a video of it in action below.
Update: I got some hands-on time with this after the presentation. Judging from the time I played with it, it's fun but frustrating. Like I said, if you've played Super Mario 64 before you'll feel right at home. It borrows the same camera controls and kill screen, something you'll probably see a lot if you're playing a badly designed level.
What's interesting here is that the creators, the guys from Minor Studios, could have launched this a few weeks ago at the gamer-centric Penny Arcade Expo (PAX) but chose to do it here. When I asked creative director Dave Werner why he'd pass up the chance to show this in front of more than 58,000 gamers and industry analysts, he told me he thought he'd get more leverage by launching it at this show.