Out of interest, is %XDG_CONFIG_HOME%/unity3d/vfqd/TerraNil (~/.config/unity3d/vqfd/TerraNil if XDG_CONFIG_HOME isn't set) getting created, and if so, is there a Player.log in there (if so, does it have anything that you're not seeing in terminal output)?
Have you had any success running other games using the Unity engine like this? It's not something I've attempted and I don't have a second machine on hand at the moment to test with.