Goal

A grid and a copy with one tile changed take turns on screen, with a blink between them. Find the tile that changes and tap it. Find as many as you can in 60 seconds.

How it works

• The change can be a tile's colour, the symbol on it, or (from level 5) a tile appearing or disappearing.
• A wrong tap costs a second. After two, the answer is shown and the next grid comes.
• Two first-try finds in a row move you up a level; two answers shown in a row move you down.
• Higher levels bring bigger grids (up to 8×8), shorter glimpses and longer blinks.

Scoring

A first-try find earns 3 + the level, plus up to 4 for speed (under 2 seconds gets all 4), plus 1 for every 3 first-try finds in a row (up to +3). A second-try find earns half. An answer that has to be shown costs 2.

A note on the flicker

The grid blinks gently, about twice a second, under a soft grey mask. If flickering images bother you, skip this game. With Reduce Motion turned on in your phone's settings, it runs slower.

Change Blindness

Without the blink, a change jumps out at you. With it, you only see a change where your attention is — so finding it means scanning deliberately, tile by tile.

Focused Scanning

The same skill spots a typo, a missing item, or the one thing that's different on a busy screen.