Devices like HoloLens and Tango provide powerful spatial awareness capabilities that go beyond simple AR to enable truly Mixed Reality applications. Leveraging these capabilities requires an understanding of these technologies as well as new ways of thinking about user interface design and gameplay. Aaron shares his team's experiences developing apps for spatially aware devices, including Behemoth which won Best Spatial Mapping at the SFVR HoloLens hackathon and Ghostly Mansion which won Best Entertainment/Game app in Google's Project Tango development contest. He will discuss how these devices differ, how he approaches design to leverage their unique features, and lessons learned along the way.