Wilderness Tag features a series of pillars dotted around the entire of the wilderness, with players being invited to tag them, similar to the way the Agility Arena works but without the timers. Players who successfully tag all the pillars (featuring various levels of difficulty) are rewarded with a generous helping of combat XP in the discipline they choose. Be careful, though, it is the Wilderness after all.
I would consider the beacon lighting game you can play once you have completed the quest "All Fired Up" to be the evolution of Wilderness Tag. All the original Wilderness Tag really involved was running around the Wilderness lighting beacons!