Great concept
The game is very attractive and has some depth for the quite simple movement mechanics.
But being so simple, the movement introduced limitations to the game and applicable strategies. If you played the right tricks at the start, by the tenth turn you should have a stable territory and a province or ally.
Then you're left with slowly pressing the rest of the field for ten or twenty turns - depends on AI difficulty. In hard mode (which takes me ~32 turns), the side of origin is covered in tank units (if you bother moving them out of cities).
Something like a train as Leafsnail suggested to connect four cities along the sides of the map, where if you capture two connected cities, you can move a unit between them in one turn. This would help end the game faster and add a bit of strategic edge by adding value to special cities, and is not too hard to add for AI to consider if it is written as I think it is.
A note on docks, their placement seems to be a bit unstable. One dock per five tiles along the same water border could work better.
...I think that's everything.
I'd be interested in reading about how some of the incredibly complex computations were implemented. ;D