Please, make terramorfing much dificult: i saw when you dig it as a simple rectangular passage. Please, 1) make necessity to install block's from wood. And make it temprory if wood not applied for fixation; 2) make passage not so rectangular, looks weared
1. Tunnels have to be reinforced with wooden supports or they will collapse in 2 days, supports do require to be repaired as well. 2. Square tunnels will be decorated later AFAIK. So they will look much more real.
Please, take time to read FAQ instead of suggesting features that have been already implemented.