Looks like the first-ever game from the "Forza Horizon" franchise to be available on steam is going to be its "Forza Horizon 4".
The game is going to allow crossplay between Xbox, Win 10 PC, and xCloud. "Forza Horizon 4" has been receiving multiple expansion DLCs and Battle Royale modes for some time now. The game has had a "Halo pack" and "Lego packs" before. A new "Hot Wheels expansion pack" is also on its way for "Forza Horizon 4". Microsoft has distributed games like "Halo: The Master Chief Collection, Sea of Thieves, and Microsoft Flight Simulator" on steam before which were successful on the platform by becoming top sellers.