I think we need some open world RPGs!
Pathfinder Adventure Card Game: core set would be ideal. Everything is abstracted to the cards, no map, etc. The game is no longer being developed and the last expansion has been released. The developers could even update the old decks (second and first edition differ somewhat). Since the game is no longer being developed, Paizo might be willing to let it be used here.
The Isofarian Guard. This is by far the best open world RPG. The game recently was released for its second printing, likely few changes in the future. They might be willing to release the rights to BGA.
Xia -- also no longer being developed, currently in a kickstarter at Gamefound with Arydia: the Paths we Tread. Since it is no longer being developed/upgraded, the makers might be willing to release the rights.
One of the HexPlorit games, one of the earlier ones in the sequence.
Because of costs, you could probably charge a small fee to play them.