The original creator, Hakkyu Kim, of the classic Korean MMO Ragnarok Online has been at work on it's spiritual successor named Tree of Savior.
There is a quasi-sequel of sorts called Ragnarok Online 2which has already been launched and is significantly different from the original since it is completely 3D. It is also F2P. While the creator had a hand in this game's development, he left long before it was ever released.
This game however returns to its 2D roots (with 3D backgrounds) and seems to boast a fantastic soundtrack.
Now however the animations look very fluid, the art style is very rich and there is an active jump ability which greatly accentuates the action elements of the gameplay. Also the game features 80 classes and over 200 unique boss monsters roaming the world.
First gampeplay trailer
I first found about this in a Kotaku article and I'm very excited The game is currently still under development and a test phase will roll out in February 2013.