Thank you! I'm glad you like it! If you're still interested in the occlusion, it has two parts: first, each wall/floor/prop compares it's y-value to yours. If it's above you, it's always hidden (with the exception of some exterior walls). The second part, for walls only, uses triggers to determine which room you're in. Each wall is assigned to a trigger volume, and if the player is inside, the wall is hidden.