For context, I am creating a HOI4-style strategy game set in the Cold War. The battles will likely be turn-based rather than involving maneuvering troops on the map.

A large part of the Cold War involved various proxy conflicts between the two global superpowers, the Americans and the Soviets. If I make it do that the player is only able to intervene in these proxy conflicts, things like “mega-factions” (the sort you see in games like HOI4 that are a pain to deal with) would no longer be a problem, and it also means a lot less work for me to add all the different factions joining in to create a huge WWIII.

However, if I limit the player to only intervention in other countries, that would limit the alternate history scenarios the player can take, and it would also mean that many countries could effectively become NPCs. I could implement a civil war mechanic, where certain focus paths will lead you to a civil war between two or more factions within your country, and you could seek intervention from the major powers. This would help countries in Latin America, Africa, Asia, etc. to be more fun to play if there was no direct war mechanic.

Finally, if there was a direct war mechanic, how should the game react to the Americans and Soviets being in direct conflict? Should the game end once a nuclear weapon has been fired, indicating that nuclear annihilation has occurred?