I see a lot of people - I'm one of them - find games in which players just stack round after round uninteresting. Here is a simple idea to stop unlimited stacking.
My inspiration for this is the board game.
In then board game there are a limited number of armies in the box, the same amount of each colour. When there are no armies of your colour left you get no reinforcements until you lose some men.
I can think of a couple of ways this could be used as a new game type.
1)The army limit is a multiple of the number of territories on the map
2)The army limit is a set amount
For (1) maybe the person setting up the game could choose the multiple from an allowed range
For (2) there could be a number of options for whoever sets up the game eg, 200, 500, 1000 or maybe just choose a number between an upper and lower limit.
This is a straightforward way to set an upper limit on a players armies. It would also lead to a situation where all players became increasingly nervous as someone neared the limit and had to attack.
I realise the situation is different in fog where you don't know how many troops your opponents have. Which could make you even more nervous, because somebody, soon, will have to attack. But you could get a rough idea from their reinforcements and how many attacks they are making.
Though I can imagine being a player in a no spoils fog game, approaching the army limit and realising that if you don't do something two things will happen. First everyone will see your reinforcements drop and if you have lost no territories, or bonuses, will know how many troops you have. Second, everyone else will start to narrow the gap on your troop count.
So fog or not, I think this will promote a more attacking style of gameplay and lead to some new stategic considerations