The global beta for Project Spark, a game from Team Dakota that allows players to "build whatever" they wish, is now available on Windows 8.1, Microsoft announced today.
Beta registration began in June of this year, shortly after the game was announced at E3 2013. Although it's currently available exclusively to Windows 8.1 users, Xbox One owners will be able to join "early next calendar year." The beta is expected to continue until Project Spark's launch in 2014. You can watch the intro video for the beta above.
Beta registration is ongoing on the game's website.