Maplestory - MapleStory is among the most popular of MMO in the 2D area scrolling style offering a user count will into the lot of players.
TripleA - TripleA is a free (under GPL) turn based strategy game based on Axis & Allies board game.
Path of Exile - Path of Exile is a free to play online action roleplaying game that draws clear inspiration from Diablo but charts a path all its own.
Lux Delux - Lux Delux is a game of strategy and domination inspired by the board game Risk.
Dungeon Fighter Online - Dungeon Fighter Online is a Free-to-play, Massively Multiplayer Online, Role-playing, Action-Adventure, Hack and Slash, and Fighting video game created and published by Neople.
ThumbZilla - Awesome thumb stomping and kicking action game.