If you have been waiting for a new Halo game to magically appear on your PC, you will be getting the closest thing to one when the Halo 5: Forge mapmaking suite is released on September 8.
Microsoft will be releasing the free DLC to Windows 10 users, allowing them to create levels for Halo 5: Guardians and upload them to their Xbox One, or make them available to the community. The tools, which were first revealed in May, will offer mouse and keyboard support, allowing "highly refined object placement and manipulation, higher-resolution displays (including 4k) for stunning graphic fidelity, the ability to host and play custom matches for up to 16 players, and a new content browser that spans platforms," Major Nelson said on his blog.
In addition to Forge, the next free DLC for Guardians - Anvil's Legacy - will be released at the same time. The DLC will include a content browser to Forge mode as a way for the community to find all the new community-create levels; a new maps for Arena (Mercy) and Warzone (Temple); and the usual array of new weapons. REQs, customization options.
Since Guardians won't be coming to PC, it looks like Forge will need to sate your appetite until Halo 6, which should have PC compatibility via Play Anywhere.