Microsoft has started to tease what appears to be a new Minecraft game for mobile devices. The software giant used a video at the end of the company’s Build 2019 keynote today to show Minecraft in augmented reality, running on a phone. In the video, Minecraft creative director Saxs Persson leaves his phone on a bench outside the Washington State Convention Center where Microsoft’s Build developer conference is being held. A passerby picks it up and is able to see Minecraft running in AR, suggesting that Microsoft is preparing a new game.

It’s not clear what this Minecraft game will be, but it could be a killer app for augmented reality. We’ve not seen many apps or games since Pokémon Go that have demonstrated the potential for augmented reality, and Pokémon Go has been downloaded more than 500 million times.

Microsoft isn’t commenting further about any plans for Minecraft AR. The teaser also notes that more information will be coming on May 17th, the 10-year anniversary of Minecraft. Microsoft has previously shown Minecraft running on the HoloLens headset, but that was simply a tech demo rather than a new game. Microsoft’s teaser feels like something bigger, especially as it’s clearly tied to 10 years of Minecraft. We should learn a lot more on May 17th.