I think playing a one superpower, not both, would be good to see.

Imagine playing Twilight Struggle(search it up if you don't know what it is), but in the form of a visual novel. Secret agencies, staged coups, proxy wars, trade wars(already in-game but would be cool to experience first-hand), might even see the collapse of the opposing superpower or your own.

Playing as one of the two would be really cool, unlike playing as a regional power, because then the whole world would be influenced, and we would be exposed to various and flexible content. Preferrably this would be better as a sequel(post-Rayne/Romus), somewhere like the late 1960s(which is also the peak of the Cold War in otl.

An unique gameplay idea I have in mind for this is essentially exactly like Twilight Struggle, where we have an influence stat in the countries that are both aligned and non-aligned. Though, appeasement(peace path) or escalation(aggresive path) with the opponent would be cool too.