But, actually, Rivalry is three expansions in one.
In the Deal Game, there is a new Deal phase to which dice with $ faces can be assigned to, along with any die to choose that phase, plus a reassigned die, and possibly another reassigned die due to the new power that everyone has on their phase slip.
Dealers can swap assets they don't want for assets they do want. And, by assets, I mean just about anything.
Not using all your credit track? Why not trade in the top part of it to get a useful die? Or, if you're running a large economy and need a credit track that goes to 11 (or even 16), why not trade away a couple of white dice to get a larger track?
Have a bunch of extra tiles clogging up your construction zones from previous Explores? Why not trade them in for new dice? Or, a chance to draw from the bag until you find a 6 cost development? Or a pair of VP chips? Or a talent counter? Or some credits? Or, another Leader die? Or, a chance to draw a world of a desired color from the bag? Or, to turn some Citizenry dice directly into Developers or Settlers? Or...