The replayability factors for Skyrim are also there for TES IV, Oblivion and TES III, Morrowind. I've replayed each of those more even than I have Skyrim.
IMO the same can be said for all earlier versiions of "Civilization". Friends and I played Civ 1 over and over for a very long time when it came out.
Most of the others I've not played, though Wing Commander: Privateer is quite replayable, for there are a number of ways to go.