Mass Effect 3: Still disappointing players a decade after its release.
Just to note, to this day, I still have not played Mass Effect 3, despite having played through both ME1 and ME2 multiple times, a decade or more ago. And at this point, unless I happen to see it on sale for like $5 or less, I probably never will, either, exactly for the reasons explained here. The series just entirely shit the bed in the final hour.
And Pat is spot on about the Borg from Star Trek, too. The Borg were great in The Next Generation. Then First Contact introduced the "Borg Queen," which basically ruined them, and the problem was then severely exacerbated in Voyager.