Tales of Maj'Eyal has been in beta for nearly 3 years and was released as V1 a few days ago.
It has its roots in the roguelike genre but has grown into a kind of hybrid with RPG, tactical combat features and a rich custom world (for lore people there is about the size of a novel to read inside!).
UI-wise wow players will probably feel at home with the way things are setup, and also the way things work.
Each class (out of 24 very different ones) has many talent trees you can develop to make your own build (and combine it with race talent trees for even more!).
A key point of the gameplay is that there are no consumables, but everything has some sort of cooldown; making each encounter a matter of thinking what is best to use and when.
Oh and it has timetravel. As in real time travel: go back to the past, live multiple possible future and choose which you prefer, ... in the form of the Chronomancers classes!
Well really it is much easier to try it than to try to describe all it can do
Oh and it's free: http://te4.org/
PS: Warning, if you like to drool over high res 3D graphics, this is probably not for you
PS2: Warning, if you like deep gameplay and character customization, a rich world and tactical combat, you might get addicted