Guild Wars 2
Guild Wars 2 represents ArenaNet’s attempt to turn MMO convention on its ears and create an engaging game for players of all skill levels and play styles. It does away with typical things like the holy trinity (tank, healer, DPS) and eschews traditional group mechanics for open-world content, which anyone can join in on without hampering other players’ efforts. Even crafting nodes are shareable; there’s no competition for resources or other rewards.
Guild Wars 2 offers several different types of gameplay. In addition to the open-world content, there’s structured PvP, which pits teams of five players against each other, and World vs. World, a series of open-world PvP maps where players fight over castles and other fortified (and un-fortified) spots to bring their home world to victory. Characters are autoleveled to 80 in each case, so you can jump right in and start enjoying these parts of the game immediately (though the free-to-play version of the game does have its limitations).