After playing Axis and Allies for hours. I came to hate the fact that a side can produce an infinite amount of units yet, the world consists of a finitate amount of resources. Hence I devised a new system to counter this problem, which actually stops stacking and prevents build ups.
Idea 1: Triple the IPC amount of every place. Each unit requires 1 IPC maintance at the start of a player’s turn. Hence if a person only makes 24 IPCs, they can only have 24 units. Conquered land only provides 1/3 of face IPC value.
Idea 2: Each place is given stats such as, a number. This is the number of a certain type of units that the space provides to the player. For example: Place X can support 3 Infantry Units and 1 Armor. Place Y can support 1 Fighter and 4 Infantry. The player’s biggest force can only be 7 Infantry, 1 Armor, and 1 Fighter.
Now idea 2 in my opinion is the best idea. It actually requires that a player must manage his or her resources and that things are not unlimited. Of course you need to set aside perhaps 5 open slots that perhaps allow a player to have 5 units of their choosing in addition to the maximum amounts they can have. But in general I think this idea makes the game more realistic and fun, and someone cannot just build up 30 Battleships or a huge infantry stack of 30 and march in. Makes managing your resources more of a concern and makes you have a diverse army.