Yeah, I don't know if we're supposed to refer to games that ruined a franchise for us individually or games that ruined the franchise full stop.

For the latter, Psy nailed the one that sprang to mind for me. Mass Effect Andromeda. I mean, I enjoyed it enough but it never gave me any real sense of intrigue or adventure like the previous series did. From what I understand (only played a couple of Halo games), Halo 4 could be mentioned too, although clearly Halo is still going so I don't know how true that really is.

For me personally? Can't think of much outside of (again) Andromeda. Hmm. Assassin's Creed 3, perhaps, although that's heavily biased towards my disinterest in that period of time in civilization combined with the fact that my drive crashed out and I lost my save after dozens of hours of gameplay. I never had the energy to reinvest.

Duke Nukem Forever was something awful entirely but that's Duke Nukem Forever, I half expected it to be trash but just wasn't ready for just how trash it really was. I did enjoy parts of it though, but not more than I enjoyed, say, Andromeda or AC3.

I tend to enjoy games a lot so it's rare that I actually find myself put off a series entirely.