Homeworld, Freespace, Descent, TIE Fighter, Planescape: Torment, and Thief come to mind when I think of franchises that just haven't been touched in a while (or nearly forever).
As for recent sequels or additions in other franchises that might be considered unworthy, I usually try to block them out of my mind if they bother me and just pray that they don't turn into serialized abominations.
As for recent sequels or additions in other franchises that might be considered unworthy, I usually try to block them out of my mind if they bother me and just pray that they don't turn into serialized abominations.