Maybe this will solve the problem (it still needs a little bit of modifications though):
Snowy terrain: When attacking snowy territories roll a die. If you roll a 6 sacrifice 2 units. If you roll a 5, sacrifice 1 unit. A roll of 4 or less doesn’t do anything.
Desert terrain: Only tanks and aircraft can pass through desert terrain.
Mountainous terrain: Only aircraft can pass through mountainous terrain.
Mongolia–Mountainous terrain
Himalaya–Mountainous terrain
Russia, Soviet Far East, Buryatia SSR–Snowy terrain
Sahara: Desert terrain
Southern Europe: Mountainous terrain
Greenland: Snowy terrain
Alaska: Snowy terrain
Saudi Arabia: Desert terrain
*PS–I know I post things everywhere but I promise I’m still working on NA’s