I like the idea of the minigun shooter, though there was some confusion about the different modes there were and the controls. The shooting part felt very nice!
The looking/aiming part, however, did not feel so good with the way it moved the camera with the gun. It definitely caused motion sickness for me. I would try to avoid moving the camera if possible in the future.
The intro scene is really cool and I think you had a good aesthetic/art direction down. If the gameplay didn't cause motion sickness, it would be pretty great!