Alien

Puzzle · plays in your browser, no download

Where it comes from

The spot-the-impostor game, which phones have been making since about 2019 and which is usually a search: a crowd, a difference, a sharp eye. The deduction underneath it is far older — it is the logic puzzle where a handful of statements about a culprit leave exactly one suspect, and the pleasure is in the crossing out, not in the finding.

How to play

The clues arrive one at a time. Wait for them all and you will know for certain — but the clock is running and the score goes down.
A wrong touch costs you five seconds, not a life. This is a game about thinking, so it takes the thing you were spending.
The three things are colour, eyes and hat, and all three are plain to see. Nothing is hidden in the drawing.
Every crowd is checked before it is handed out: with all the clues out, exactly one creature is left. Never two.

What makes this one different

One of the crowd is not one of them. You are not looking for it, you are ruling it out: each clue at the top says one thing the alien is, and everyone who is not like that goes dim. The clues arrive one at a time, so waiting makes you certain and costs you the clock — and a wrong touch costs more every time you do it.

There are three things and only three — colour, eyes, hat — so there are eight creatures possible in all, and every clue halves what is left. That is deliberate: with six properties you would need to hold a table in your head, and this would be homework. And no crowd is handed out until it has been counted: with every clue out, exactly one creature matches, and it is the one hiding. Never two, so you never have to guess.

▶ Play Alien