If you are looking for a Forza Horizon experience natively on PC, the series began official PC support with later entries:
For players determined to experience the Mediterranean coast on a monitor, the only functional route is through Xbox 360 or Xbox One emulation (such as Xenia). However, emulation is a hardware-intensive process. It requires a powerful CPU and GPU to translate console code into something a PC can understand. Even then, "verified" downloads of the game files (ROMs or ISOs) are legally gray and often difficult to find since the game was delisted from the official Microsoft Store years ago due to expiring car and music licenses. Final Verdict If you are looking for a Forza Horizon
: Sites promising "highly compressed" versions (e.g., shrinking a 40GB game to a few gigabytes) often bundle malicious software with the game files. Game Review (Based on Xbox Performance) Even then, "verified" downloads of the game files