Similar to Civilization, it might be interesting to have players choose from different leaders with unique bonuses/tradeoffs. For example:
Win ties when attacking but lose ties when defending, encouraging an expansionist strategy
Gain interest each turn on their number of unplaced units (or unused currency if we go that route), encouraging saving that up at the cost of short-term vulnerability
A "martyrdom" ability to gain units/currency the more of their units are destroyed in battle
You gain some percentage of the first-place player's income (in units or currency) as long as it's not you each turn, which helps when you're behind but is useless when you're ahead
Gain one unit per turn in each connected cluster of territories that isn't your largest, encouraging a multi-cluster strategy rather than building a single cluster of territories
New game mechanics such as tile improvements will present new opportunities for unique variations on them.
Similar to Civilization, it might be interesting to have players choose from different leaders with unique bonuses/tradeoffs. For example:
New game mechanics such as tile improvements will present new opportunities for unique variations on them.