Another mechanic that I can’t decide if I like or not is the inclusion of your “Spirit Guide”. Your spirit guide manifests itself in the form of a bird of prey and leads you through the levels much like the old Guide Bots in Descent. To me this came across as cheating, removing much of the “what next” from the game and instead turning it into a game of “follow the leader”.
The last interesting game mechanic is the gravity. In certain spots on levels you can shoot markers while Spirit Walking causing the gravity in that room to shift to the floor of the marker you’ve just hit. Say you walk into a room and see a marker on the wall. Switch into spirit mode, shoot the marker, return to your body and now you’re walking on the wall. Just be careful that you don’t have to far to fall to the “floor”.