Halo as a franchise has always had a bit of a cold relationship with the PC. Following a disastrous port of the second game, the franchise was nonexistent on the platform save a handful of mobile spinoffs and the enduring fanbase of the first game.
Amazingly, even after EA shut down their official servers, both games still lived on, right up until GameSpy finally went kaput in mid-2014. By all rights, that shoulda been the end of the story. But where there's a will, there's a way; and the internet always finds a way.
[size=x-large]What's ElDewrito?[/size]
Long story short, "ElDewrito" is a mod of a Russia-only free-to-play FPS called "Halo Online", which was pretty much a PC port of Halo 3.
[size=x-large]Do people really still play?[/size]
Unfortunately due to the game's legal situation, the playerbase has shrunk from over five-thousand to just under five-hundred on a typical night. That's still plenty-enough though. You'll never be starved for a game of Slayer, CTF, or even SWAT sometimes.
[size=x-large]Legal situation?[/size]
Despite literal years of grueling work and commendations from 343 Industries, Microsoft themselves stepped in to pull the plug. The team's still allowed to operate their servers, but they were forced to remove download links, and any mention of the game incurs moderator action on r/halo.
[size=large][size=x-large]Alrighty then, how do I get it?[/size][/size]
Luckily, most folks were wise or lazy enough to keep the archive the game came in, so the community's free to circulate the tapes, so to speak. Literally all's you've gotta do is download the archive, unzip, and play.