Questions about mod/mod makers

[Vassili]

you could shrink the unit (morph tank) to a tiny size and use effects like its digging

That seems a good idea, the first form is the ship, the second is just the top of him who are on the ground like the full body was inground.
This solution do have the problem

you can actually out the visual mesh below ground (but not physical body)

beetween the full and small form or we can have one physical body by state?

[Red Spot]

N1, just out of curiosity. Do you know if you can spawn a single tunnel segment and than use it to spawn/hide units? (I know the side-effects arent going to be pretty, but is the tunnel functional?)

[Nielk1]

Tunnels will work, but if you are using DLL (as weaponmines would be too unpredictable) you can probably do something a bit cooler. Or maybe you could dynamically create "cave" tunnels underground and have them follow the contour of the land and dynamically collapse and dig new parts of the tunnel as you go unless you hit some area that prevents it. The code would be quite complex.