When I was a kid, doing my level best to not colour outside the lines, I always loved Spot the Difference puzzles - despite the fact that I completely sucked at them. Moonlight Differences takes the whole spot the difference thing to the next level, adding a vague narrative, and a cool scoring mechanism.
It's all very simple and basic, but it just adds something. The core idea of finding the difference between two pictures in fun, adding new ways to engage with that concept just makes the whole thing feel a little smoother, slicker.
This game won't change your life, but it will entertain you.
Moonlight Difference [Kongregate]