Visual memory

The game measures visual short-term memory: how many positions you can hold from a single glance. Research on visual memory suggests people hold about four separate objects at once, but grouping helps. A set of lit squares that forms a shape can be held as one thing, which is how good runs go further.

• Level 1 lights 3 squares on a 3 by 3 grid. Every level lights one more square.
• The grid grows by a row and a column every three levels, up to 7 by 7.
• The squares flash for 1.1 seconds at first, a little shorter each level, down to 0.7 seconds.
• When they hide, tap exactly those squares, in any order. Correct taps stay marked so you can see your progress.
• A wrong tap ends the round and costs a life. With lives left, the level replays with a new pattern. You have three lives.
• If you switch apps or tabs during a round, the level replays and you lose nothing.

• Take in the whole grid at once instead of hunting square by square.
• Look for shapes in the lit squares: a line, a corner, a block, a diagonal.
• Start with the squares you're sure of, then fill in the rest.
• Compare scores on the same device, since the grid looks different on a phone and on a laptop.