https://www.gamespot.com/articles/forza-horizon-2-getting-removed-from-sale-soon/1100-6461247/

It's the end of the road for Microsoft's racing game Forza Horizon 2. Microsoft has announced that the 2014 racing game will be removed from the Xbox Store on September 30. As part of the game reaching "end of life" status, all of its DLC will also be yanked.

If you already own the game, you can still play it, while you'll also be able to re-download it should you need to delete it to clear up space. It's not immediately clear if Forza Horizon 2's online services will remain available after the game is removed from sale.