Leave it to Microsoft to fulfill fans' long-standing wish of bringing modern Halo multiplayer to PC and then obfuscate accessing it in the most spectacular way possible. It's coming by way of Forge -- Halo 5: Guardians Edition for Windows 10. As the name suggests, the free download is for Halo's custom map toolset, Forge, and it features full keyboard and mouse control, up to 4K resolution and the ability to build stuff on PC and then play on Xbox One. The devil is in the details here, though: the Xbox Wire post also mentions that you can test levels and play them with your friends on PC.
Microsoft confirmed to Ars Technica that yep, this is what constitutes Halo 5 online multiplayer on PC. Albeit without matchmaking and being limited to playing only with folks on your friends list, that is. There's silver lining here, though: While the package is indeed rather light, at least PC players don't have to suffer through the game's awful campaign because it's not a part of Forge.