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.
Nuclear Throne - Post-apocalyptic roguelike-like top-down shooter about mutants.
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.
Enter the Gungeon - Enter the Gungeon is a gunfight dungeon crawler following a band of misfits seeking to shoot, loot, dodge roll and table-flip their way to personal absolution by reaching the legendary Gungeon’s ultimate treasure: the gun that can kill the past.
LaTale - LaTale draws heavily from some other 2D side scrolling video games to provide a great fantasy MMORPG world.
The Binding of Isaac - The Binding of Isaac is a 2011 independent video game designed by Edmund McMillen and Florian Himsl.