That man who won Nethack without spoilers... CRPGAddict?
I've won ADOM many times without spoilers, but: I was much younger (lots of time to waste), spend years on it and decision feedback in ADOM is much better (I could quit to check what intrinsic drinking from pool gave me etc.).
Reading source code is necessary to win Omega, though. No, it doesn't even help. That game was a nightmare, Jesus Christ on a pogo stick.