Glossary Entry: Moon logic

Puzzles in games are supposed to make some degree of sense. For example, if you encounter a locked door, then there should be something to unlock it nearby, like a key.

Sometimes though, the correct solution makes no sense whatsoever. This is moon logic - a type of logical deduction that could only work in the mind of an alien being.

Point and click adventure games are notorious for this, but any game that relies on inventory puzzles can suffer from moon logic.

For an example of moon logic, let me walk you through one of the puzzles in an old point and click adventure I used to play.

You start the game with a strange key, and as you explore the local area, you'll encounter a room containing a locked door. Using the key here won't work, as this isn't the right lock. There are no other keys to be found in this part of the game, so how do you open the door?

Well, that's where the moon logic part comes in. The correct solution is to search a nearby pier and collect a dead fish. Telling your character to use the fish on the door has them use the fish's tail as an improvised lockpick, opening the door.

There are no hints about this anywhere in the game, leaving players to try every possible item they've collected so far on the door in the hopes that they'll stumble across the right one.