Perhaps one of the worst cases of poor timing in wargames was the appearance of Red Storm Rising in 1989. While it was trying to capitalize on the earlier success of the Tom Clancy novel by the same name, and doing a pretty good job at depicting the sweeping scope of the battle recounted in the book, within a few months of its arrival on store shelves the Cold War ended.
Fortunately for everybody, it didn't end with the bang premised by the book, but peacefully.
Still, the end of the Cold War pretty much ended the reign of what had been one of the more popular genre of wargames -- "future history," particularly the NATO v. Warsaw Pact big show.
While there would still be some future history games published over the years, and at least one scenario imagined by several of them came true when the U.S. went Back to Iraq, they stopped being the major force they had been.
It's too bad, in the case of Red Storm Rising, because the game provided a reasonably accurate wargame that was playable in an evening. When linked with The Hunt For Red October you could play out the whole NATO v. Warsaw Pact Air-Land-Naval scenario in an afternoon.
There' still some residual interest in both games and they get played occasionally, according the BGG reports, but I think they'd have had more of a chance to build up a fan base if the wall hadn't come down so soon after they were published.