I love the concept of the game but here are a technical few things to just fix and it will be perfect:
1. Reduce the raycasting distance - make it shorter, I can open doors from huge distances
2. Make simple checkpoints, I die and I start all over again.
3. The 3D text on the walls is clipping trough the solid objects, its easily fixable, you can use this shader: http://wiki.unity3d.com/index.php?title=3DText
Great potential, like it!