The staff at Casual Game Guides has been playing the game Riot Games’ League of Legends, a free real-time strategy MMO that’s been around for a couple years now. The game qualifies as a casual MMO in that it is simple to learn and play, and the game rounds are short (20 minutes or so), which is one reason why it's so much fun to play.
It doesn’t take a huge investment like other MMOs, and if you have a half hour here or there, you can squeeze a game in. The game is inspired by Warcraft III (yes, the game preceding World Of Warcraft.
TNS: "A League of Legends game mode, Arena, will return with some major changes that may breathe some life for a stagnant game."
ESTNN writes: "Hwei, LeBlanc and Ryze stand above the rest as the strongest players in the League of Legends 14.8 mid-lane due to substantial buffs in their scaling, base damage and crowd control (CC) respectively."
ESTNN write: "Our updated guide on the latest champions coming to Summoner's Rift."