I played the demo for Over the Hill and enjoyed it. As others said it's pretty calm and slow-paced. It's not really about firm objectives, but rather you decide where to go and what route to take. Some people don't like the physics but I thought they were okay. You'll probably want to upgrade tires and suspension right away since the game is all about traction on rough terrain.

Anyway, try the demo if it's still available, since it's free.