Microsoft pulled the plug on Windows XP and Vista years ago, but the vintage operating systems have still been supported by an ever-dwindling number of games - a number which will dwindle further when League Of Legends ditches them in 2019. Part of what made the MOBA a mega-hit was that it can on pretty much any PC built in the past 15 years, but so few of its players still use XP or Vista--under 1% for XP, developers Riot Games say, and less for Vista--that Riot say it's not worth the effort of keeping it going.
"It's getting harder every day for us to maintain a secure League of Legends experience for the very small number of League players still using XP, requiring a disproportionate investment from our engineering teams," Riot said.
Not to mention that with Microsoft no longer updating either, they're mighty prone to exploits, viruses, and other awfulness so you really shouldn't still be using either online.
"Usage of Windows XP has been falling rapidly over the last few years," Riot said. "When we most recently pulled data, we found that under 1 percent of players globally are still using XP. Usage of Vista is even lower. And we think that by the time we end support for the operating systems next year, even fewer will be playing."
LoL will officially end XP and Vista support in Patch 9.10, due on May 14th, 2019. This being a multiplayer online game, players will need to get that update to play, cutting off the XP and Vista folks. Which sucks for them.
Fellow crappy old gaming PC mainstays Blizzard and Steam both held out for a long time too, but Blizzard phased out support for XP and Vista in their current games in 2017 and the Steam client will ditch it in 2019.