If you are looking for a TableTop RPG with plenty of depth, customization, and some Sumerian mythology thrown in there, I think there might be a game you need to check out. Now I want to go ahead and apologize for not writing this up sooner as the KickStarter for ANKUR-Kingdom of the Gods is now past the halfway point, but this is still definitely something that might interest the TableTop aficionado out there.
The game is based off a D12 variant, and features five different playable races, seven castes (or classes), two different worlds where there are plenty of potential twists and turns as well as ways to build up your character. This is the first time that the creator, Christopher Miller, has attempted a KickStarter, and this definitely is an ambitious one to start with.
Here's a look at the trailer, unfortunately there's not a whole lot of depth to it, but I can tell you that this is indeed a TableTop, pencil and paper, Sci-Fi, RPG.