Wow, it took me about five minutes to find out what this is. The headline certainly doesn't say it. The faq doesn't answer it, the wiki has no such information. I had to fire up Acrobat Reader first, download the PDF manual, and scroll down a few pages. If it hadn't been for the upvotes on HN, I would've completely missed it...
"A rapid prototyping, livecoding and playing/learning environment for 3D graphics, sound and games. Extends PLT Scheme with graphical commands and can be used within it’s own livecoding environment or from within the DrScheme IDE. Fluxus is crossplatform (Linux, Windows, OSX), and is released under the GPL licence. "