The worst part about RIFTs is that, even if you use just a core-rules game, with none of the expansions, you will have a party where at least one player feels useless and at least one player just dominates. I've been in games where the Rogue Teacher (me) sat around and did next to nothing while the glitter boy destroyed everything in sight, and the wilderness scout made some rolls to get us to the next fight, and then repeat. And when we got to a city so I could be all Rogue Teacher-y.... the other two players complained that they had nothing to do, and the encounter got waved by - because, at least in those combats, I could shoot my pistol for 1d6 MDC or whatever.
That's RIFTS.