Vivecraft, with an HTC Vive and motion controllers and roomscale to walk around a bit in, is currently a killer app for VR. It works so well and the dev is making almost weekly major updates to the UI ...
While there are literally dozens of games planned with support for the Oculus Rift VR headset, I’m going to go out on a limb and suggest that few will feel as natural as Microsoft’s Minecraft.