Stats: Things like...
-Class(Could be things used commonly for ranks of roleplay groups, like Warrior, Medic, Hunter, etc.)
-Hitpoints(For how much damage you can take, except that you do not die and instead only get knocked out.)
-Energy(For doing actions like jumping, running, or any combat move.)
Magic(For doing things like throwing fireballs, or having flaming claws.)
-Accuracy(For chance that you will hit or miss.)
-Damage(For the amount of damage that you will do.)
-Armor(For chance to take no damage even when hit.)
-Agility(For chance to passively dodge.)
-Thirst(If you don't drink often enough, you would lose slowly hitpoints down to 1.)
-Hunger(If you do not hunt often enough, you would lose slowly Energy down to 0, and therefore be unable to perform any combat action.)
Combat:
-An option to ask another player to 'duel', perhaps for the purpose of a Roleplay.
-Several Combat actions such as Bite, Slash, Headslam, Run.
-Actions could be colletable things that you earn by doing something in the game, such as finding it laying around.
-Being Knocked Out would mean that you can not move and would simply rest until at least 1 hitpoint is restored, then it would be up to you to restore the rest of the Stats.
Prey:
-Something running around that you can hunt to regain Energy.
-Would not cost energy to hunt.