There have been games that strove to do something like that -- though, usually, based directly on the real world rather than a generated one, and usually with a limited array of real-world country choices, and sometimes with a fantasy twist.

Balance of Power (both the original and 1990 editions; allowed play of the USA or USSR only) and Shadow President (allowed play as the USA only) come to mind; ISTR one that allowed play as a wider variety of real-world nations, but can't place the name.