MUX is an upcoming 2.5D MMORPG developed by China’s The9. If you have been following the gaming industry news around the world, you would have known The9 was the ex-publisher for World of Warcraft China.
After losing the rights to the game, Th9 learnt a hard lesson as it saw its stock price plummet and had to relocate or sack around 50% of its staff, as most of them were working for the WoW title. Since then, The9 has started their own studios (below) and actively developing their own games.
MUX bears striking resemblances to Webzen’s MU Online, the only reason I can think of is that The9 is the publisher of MU Online in China, and Webzen has given Th9 rights to alter its source code.
Not much is known about this game in black and white or in screenshots other than some boring artwork (below), but the trailer shows some ingame footage.