Civilization 2 was first released in 1996, which is approximately forever ago. Reddit user Lycerious has been playing the same game of Civ 2 for the past 10 years (!), and his virtual world of 3991 A.D. is a "hellish nightmare" devastated by global warming and perpetual nuclear war.
The population of Lycerious' simulated world peaked some 2,000 years ago, at about 2,000 A.D. or so, which ought to get you thinking. Since then, things have degenerated a little bit: there are three superpowers left (two controlled by AIs plus Lycerious), and they've been at war with each other non-stop for 1,700 years and counting. Since everybody has nukes, everybody uses nukes, and as a result, the ice caps have melted 20 times, making swamps out of all of the land that's not already contaminated with nuclear fallout. Famine and war have killed 90% of the population of the world, and there's no end in sight: every time a peace treaty is signed, the AI breaks it (with nukes, usually) on the very next turn.
Despite the centuries of vicious stalemate, Lycerious remains optimistic: "My goal for the next few years is to try and end the war and thus use the engineers to clear swamps and fallout so that farming may resume. I want to rebuild the world. But I'm not sure how." So far, he hasn't been able to win the war and the AI refuses to make peace, but there may still be some small hope.
Reddit users have suggested building up an army of engineers to resume food production and help stabilize the climate before the next ice cap melting event (which happens every hundred years or so), followed by a change to Fundamentalism, a huge military build-up, and a covert nuking of every enemy city at once in concert with a ground invasion.
Lycerious estimates that executing this strategy will take him "many months in real time," but after 1,700 years of strife, that's not too much to ask, is it?