Runescape

Runescape is a massive multiplayer adventure, with monsters to kill, quests to complete, and treasure to win. You control your own character who will improve and become more powerful the more you play. Do what  in the world is up to you! you will meet many other people in the world who you communicate with. Make new friends and go adventuring together to stand a better chance against the stronger monsters. Perhaps you want to trade with others for valuable goods . Or you can fight with like-minded people to try and steal their treasure.

More info,link to official site:www.runescape.com