The reason for the blocking is because there are like 5 versions of the game all licensed by different companies. Nexon only licensed it in NA while other regions it was licensed by other games.
Anyways, I've been playing a mercenary and wow, it is crazy fun. Combat gets really hectic in abyss mode.
My only beef with the game is that hard/master modes are both way too easy. You NEED to be in abyss for it to be challenging, even if you're playing solo.