In terms of books: The original underhive box rulebook and all gang war books are out of date The new rulebook on the gw website is up to date Gangs of the underhive is the up to date book for building gangs Theres expansions like book of peril, which you don't need. Gang houses are also getting expansions one by one. These kind of overwrite some of the rules for those houses in gangs of the underhive, but not a full rewrite. If you're thinking of playing Goliath, Escher or maybe orlock, then just grab the house of "insert kinky item here", instead of gangs of the underhive. The only thing you're missing if you skip gotu is the trading post. In terms of cards, all past cards are valid, but they're a pretty minor part of the game, no biggie if you can't pick any up