The title says: Grand Theft Horse. The description says:
"DISCLAIMER: Any elements of the game "Rustler" that are inspired by elements of the pop culture are to be seen a parody or caricature."
Why does it have to be a parody only of games? Parody in general is protected, as the games show.
Saints Row is a parody, as confirmed: https://screenrant.com/best-parody-video-games/