Just revealed recently after being announced some 6 years ago, Memory of Aria is the first online game from Korean developer Curoa. According to the introduction, players will travel to the past and future to change the course of history. A time travel sandbox? Not really from the looks of it.
There will reportedly be no class system, with players able to customize their characters to a extend. It is also touted as having non-target action combat, which you can see in the trailers here. Focus Group Testing (FGT) will begin later next month.