Spintires Off Roading!
Spintires is a insanely realistic off road game where you have to transport good across rough terrain, through forests and dirt tracks. Basically Euro Truck Sim but its off road. There is a free tech demo out at the moment which is worth the download. Beta is being released this month which has alot more features and up to four player online. I for one will be getting this as i love most things off road but i still think people who dont know care for off roading will probably enjoy too.
Check out there website here
http://spintires.com/Also here is a video of some beta gameplay that some guy has got his hands on early.