Announced by Gumi Japan about a month ago, Serencia Saga: Dragon Nest is yet another ARPG based on the popular Dragon Nest. It is now available on iOS and Android platforms in Japan, however the servers are still in maintenance (apparently due to overwhelmed traffic) till now.
There are four playable 4 classes – Warrior, Archer, Cleric, and Sorceress available at the start. The game features a brand new storyline too, setting its background in the world of Serencia. You can play the game in either landscape mode or portrait mode (choose whatever suits you!). Co-op plays up to 4 players are available for the boss raid, not to mention the customizable characters and costumes as one of its biggest selling points.
Not sure about when will the server finally reopens again, but you can grab the game now and wait for the servers to online if you want to!