Circuit IQ

Two tiles go together when they match and a line can be drawn between them that turns no more than twice.

The rule came out of a Japanese arcade cabinet in 1989. Circuit IQ is the rule rebuilt, and now it is two games in one app, a switch apart.

COLOUR

Tiles carry a colour and a mark, and a pair has to agree on both. Thirty-two boards across eight worlds, each with its own idea: plain, blocks, gravity, slide, columns collapsing toward the middle, rows splitting apart, shear.

IQ

Same rule, different tiles. Every tile is a figure: one of sixteen shapes, one of five fills, up to three side by side. Under the board sits a key that says what "match" means on this board, and the key changes every four levels:

• Match — figures that agree in everything.

• Cue — the key names one thing a pair must share, shape or fill or count, and changes its mind after a set number of pairs.

• Code — digits on one side, figures on the other, and a table saying which is which.

• Trail — a cursor and an ordered sequence; clear the next figure, and only that.

• Steps — the partner is one step along the scale: one fill heavier, or the next shape.

• Sum — two counts that add up to the target.

• Matrix — three-by-three blocks, each with a rule and one blank. Work out the missing figure and route it in.

From the third world some figures are turned, by a multiple of fifteen degrees. From the fifth, pairs of tiles quietly change places while you look.

It is a score, never a test. Nothing here measures anything about you; it is a puzzle about reading a rule and applying it fast.

THE SITTING

Ten boards, two minutes each, one after the other, and an index out of a thousand at the end: completion, speed, and every wrong pair counted against you. Your best index is kept for each game.

TWELVE POWERS, AND NO MORE COMING

Reveal a pair, shuffle, take any pair by hand, tilt the phone and watch the tiles fall that way, break every tile of one kind, freeze the clock, turn the settling over, take a pair at random, rotate the board a quarter turn either way, stand every turned figure upright for twenty seconds, or swap two tiles of your choosing.

They are a budget for the entire run, not an allowance each level. The only ways to gain more are to clear a level with time to spare and to finish a world. Spend early and the last world will find out.

SAY IT

Switch on the microphone and a key appears along the board's edge: numbers over the columns, letters down the side. Say "B3 E7" and the pair is tried. Say "Reveal" or "Rotate left" and the power is spent. Everything is recognised on the phone itself; nothing you say goes anywhere.

NOT SURE WHAT A BUTTON DOES?

Tap the ? beside the i, then tap anything and it explains itself. The field guide behind the i is the whole game with pictures.

CHAINS, STARS, LIVES

Pairs found within three seconds of each other chain, and every link is worth more than the last. Every level cleared earns one to three stars. A run has three lives: running out of time costs one and offers the level again; finishing a world gives one back.

ONE BOARD A DAY, TWICE

Every day the date names one level of each game and deals it. It is the same board for every player, everywhere, and you get one attempt at each. Clear it on consecutive days and the streak builds, separately for Colour and for IQ.

ALSO

• Relaxed mode: no clock

• Replay any cleared level, restocked

• Stars, best score and fastest clear per level

• A hundred badges per game: bronze to platinum medals earned from your records

• Game Center if you choose it: leaderboards and sixteen achievements — or keep it all on the device

• A light look for IQ, dark for Colour

• Thirteen tracks of music to pick and order, step through, or keep soft

• A keyboard or game controller drives everything, the Xbox Adaptive Controller included

• Close the app mid-level; the run waits

• iPhone and iPad

No accounts of our own, no ads, no tracking, nothing collected, and no in-app purchases. Just the board.