My top 6 rarest achievements on Steam are from the same game, Lushfoil Photography Sim. I'm in the top .01% (that's point ZERO one percent) for the achievement "complete!" As soon as the game came out, I was sure I would 100% it. I love when a game rewards you for exploring every inch of a map, and doesn't hold your hand. Some of the items and collectables are only found on certain variations of maps that you have to do a specific set of actions to unlock, and the game isn't exactly up front about what those actions are. So it was a lot of trying to get into the mindset of the dev, and just experimenting.