I've been thinking for a while about how Hannibal's crossing of the Alps was a huge game changer (even though Carthage still ended up losing the war) and since the Carthaginian civ no longer has that ability, I've been left wondering how one could emulate that part of history in this mod. And then it occurred to me, what if a Great Generals could be stationed in a Mountain tile and let military units cross that mountain tile? It wouldn't be too overpowered since only that tile could be crossed (giving an appropriate amount of time for a counter-attack) but could potentially change the tide of war. Maybe a Great General can be expended on a mountain tile, allowing that tile to be passable for your units for 15 turns? Just a random thought.