The Cortex book , if I recall correctly, came out rigt before or right after Supernatural. It has all of the fixes
As mentioned above, not as a stand alone. Both Leverage and Smallville are Cortex+ games. Each is its own variation of Cortex drawing mechanics and philosophy from indie/Forge games (which I tend to dislike).
Leverage is much closer to traditional Cortex in that it keeps the abilities. However, it does away with the skills and replaces them with five roles. Characters have ratings in the various roles. So, it is like having ninja +4 and bard +3 in some indie games.
Smallville does away with ability scores and skills completely. Instead you are rated on values: Duty, Glory, Justice, Love, Power, Truth and relationship die ratings for each PC. Developing the relationship web takes up a lot of character generation.
The game is influenced by Primetime Adventures and several indie/Forge games and Cam brought in developers from PA and other games to help develop it. I despised PA and, while I find a couple of Smallville's mechanics intriguing, I don't think very highly of it either. I think it is a RPG.net darling and overrated over there. I wish Cam would stop trying to be gimmicky with the system under Cortex+ and go back to using classic Cortex. The relationship die could have worked with it as a bonus die in appropriate situations.