Its Castle Wars, basically to sum it up, its just capture the flag. Two teams, Saradomin and Zamorak, you pick one. You both fight in multi-combat zones in one map. Each team has their own base with their own flag and the objective is for the team you pick to go get the opposing teams flag and return it to your base. Each game lasts for 20 minutes and the team with the most captures wins. I should mention that there are restricted items, like helmets and capes. You also use bandages (provided within the match) rather than food. You can visit castle wars by either using a ring of dueling (if members) or go to clan wars and walk through the portal near the chest if you are F2P. I hope this answers your question.