Basically name a video game series that had potential, but the developers manage to screw it up. Express your opinion and don't be afraid, if you don't want to express then just name the game.
I'll start off and say the developers fucked up the Silent Hill series. It started off great with the four SH games, but after the original Team Silent developers disbanded, and gave the ip to different developers. The series has been in limbo ever sense. The newer SH entries isn't bad (except Shattered Memories) but its not on the same level as the older SH games. It lacks the tension, creepy atmosphere, narrative, and creative design.
As current gen technology is now, you would think the devs would bring the best aspects out of the SH series, but it just never happened. For some reason the SH series never reach the peak that it once had, and maybe will never see it again. So far there's been a streak of lackluster SH games.
Silent Hill :Downpour the latest in the series sealed the deal. It had good intentions with a more open-world SH game, but the clunky combat, stupid unrewarding side missions, crappy inventory system, uninspired design, buggy and weird graphical glitches, and a story that was just meh didn't do the game justice. After this game I lost complete faith with the developers.
I came to the conclusion that the series will be half-ass, unless other devs or Hideo Kojima decides to takeover. Sense he's shown interest of working on the series. It would be nice if Kojima put some of his magic on Silent Hill, and restore it back to the great survival-horror it once was...