After four months of public testing on PC, exclusive to Windows 8.1, Microsoft's game-making game Project Spark has jumped to Xbox One. Spark has all sorts of easy-to-use tools and assets to create your own fancy 3D games, and you can play other people's creations.
Signups are open on the official website. If you're already signed up for the Windows 8.1 beta, you're automatically in it on Xbox One too.
Projects are saved in the skies above us as digital clouds, so you can swap back and forth between the Xbox One and Windows versions by inhaling deeply then spitting into your disc drive.
Here's a recent stream with Team Dakota discussing the One beta and playing a few creations: