I'm uploading full versions of underground city layer below the ice. I've managed to finish all a bit sooner than expected, I had several of my teeth removed on Wednesday so I took some off work time and I've spend some time on finishing this biome up.
As I've mentioned in previous posts, my proposition here is to use this pack together with the upper, surface level sheets (2 underground, 2 corresponding surface sheets for example) using elevator hexes to move between map levels.
Rule wise - I think it requires some additional testing. While checking the map out, I've took this approach: while you move into "elevator" hex, you can decide to use 1 additional movement point to "teleport" to the surface and continue your movement from this point on. I think it's pretty cool allowing your faster units to flank the enemy, while not disabling heavier and slower guys to take part in the fun, due to very heavy movement costs of using the elevator. However - it's just a loose suggestion from my side. Have fun!