This is Space Pirate Trainer for the HTC Vive. You hold two laser guns and shoot at waves and waves of drones. It's very easy to explain, and I take you through the different weapons available in the preview build sent by the developers in the video above, but seeing it is only part of the story.
"Space Pirate Trainer is a virtual reality game that makes full use of room scale VR and tracked controllers," the official page states. "The game will show you how good you are at being a Space Pirate and/or train you in becoming a better one. Not that you’ll probably ever need to be, but still ..."
The game, even in this early form, is physical in a direct and satisfying way. You have to learn how to aim well with both hands, and know when to get your shield out. You also have to master the use of each setting on your gun, but that's only part of the experience. You also have to learn how to move your actual body away from enemy fire as you take advantage of the time dilation that happens when you're attacked.
That sometimes means ducking or stepping out of the way. During one memorable session I dropped completely, hit the floor hard on my back, and returned fire backward as I rolled around to dodge the second barrage of enemy fire. I've shown this game to many people and everyone gets it instantly, but it takes a very long time to master. The motion-tracked weapons and ability to dodge in the room-scale VR gives you a surprising amount of creative freedom, and it's great fun to just jump in there and start to play in that space.
This is the sort of experience that really shows off what the Vive can do. It's physically demanding, it's challenging and it's something that can only somewhat be conveyed in words or video. Developer I-Illusions will release Space Pirate Trainer this April, alongside the Vive.