Paleo Survival MMO game. All players are required to use an omnidirectional treadmill for movement control, and your nutrition for the day is determined by the resource nodes you harvest. You have to form raid parties and take down whales, mammoths, bison, razorbacks, or aurochs in order to get larger quantities of meat. If you die in the game, you are required to donate one unit of whole blood, and will suffer a crippling movement speed malus every time you log in, until you do. (So don't die more than once every two months.)

I should stop now, before someone starts thinking this might be a good idea.