Yo dawg, we heard you like games... Yeah, so remember Project Spark, that "game-making game" that was so tantalizingly, so awkwardly revealed to us by Microsoft at this year's E3? Its website is now accepting sign-ups for beta, so get on over there if you're keen to craft some whimsy.
The site looks a little hastily slapped-together, but signing up is as easy as inputting your email address (and wrestling with a CAPTCHA). No word on when they'll let users start trickling in, but once you're there, you'll be able to put together game worlds, determining the placement of valleys and streams and even deciding how things like flowers should act. It probably should be mentioned again that for PC users, this is only available to those with Windows 8—kind of a bummer, but hopefully the ease with which one can build their happy, cloud-shrounded world of dancing flowers will make up for that. Here's a video of the sort of things you could theoretically build in Project Spark: