http://www.openkore.de/
I dont know if this is old news or not but I recently found this.
Pros:
Its free
art done mostly by the writer (saves you from image and description confustion)
built on a heavily customizable rule set (but you will need to find you way around it first)
Calls is self a bit like Fallout 1&2 + SR3 (At least inpsired by)
Cons:
Rules can be a bit hard to grasp
Mathsy
some things seam way OP (but yet to really play a game to see if that is true)
So any one know of this already and what are your thoughts?