While there is no permanent way to get a "free" standalone copy of The Elder Scrolls IV: Oblivion that you keep forever without a subscription, there are several legitimate ways to play the full game for "free" through existing memberships or frequent deep discounts. Current Ways to Access Oblivion "Free"
If you are deciding which version to play for "free" via Game Pass, the version offers significant upgrades: Oblivion Free Full Game
If you do not have a subscription, the game frequently goes on sale for a price low enough to be nearly free: While there is no permanent way to get