For instance, take this puzzle.
When you weren't looking, someone came by and gobbled up your fish dinner. The three brothers near the scene of this dastardly crime had this to say:
A: "Me? Oh yeah, I ate it. It was good too!"
B: "I saw A eat the fish right up!"
C: "B and I didn't eat that fish."
One of these three brothers is lying to you, but which one is it?
My first decision was that B is the liar - A ate the fish, but B didn't actually see it. This allows both A and C to be telling the truth.
The answer given by the game is that C is the liar, because A and B have corroborating stories, and if only one is the liar, then it must be C, and therefore both A and C ate the fish.
This makes no sense to me, possibly because of a translation error... B says he saw A eat the fish "right up", which strongly implies that A ate the entire fish. Which makes B's story not compatible with the game's solution. My answer makes more sense. In my opinion.