Some games have afterthought multiplayer. That's what I call any game where clearly the original design doc was this super clever singleplayer game, but the publisher or whoever said "OK, yeah, but it would really help if we could put a 'multiplayer' bullet point on the back of the box."
Did Dead Space or Resident Evil ever need multiplayer? Not fucking really, but they've both experimented with it, largely unsuccessfully.
Did it help the sales of either game that Mass Effect 3 or Bioshock 2 or Spec Ops: The Line had multiplayer? Doubts.
Did anyone play the multiplayer in Metroid Prime 2? If you did, may god have mercy on your soul.
Did anyone play the multiplayer in Pikmin 2 or 3? OK, so no one did, but I'm actually going to stick up for this one, because those modes are actually fucking awesome. The hardest part is just finding someone else in your friend group that actually has any idea how the fuck to play Pikmin, because otherwise your micro due to owning the game is just going to autowin you ever game. But seriously, those modes are great.
So anyway, if you can think of a game where CLEARLY it began its life as a single player game idea, and somewhere along the line they came up with a multiplayer mode to bolt onto it, BUT IT WAS ACTUALLY PRETTY GOOD, vote yes, and share your experience with it! If it's all been bad for you, vote no, and feel free to bitch about just how stupid and pointless some particular multiplayer mode was.