The Doppit Almanac · No. 38

Roomit

Shade each room to its number

What it is

Roomit is Heyawake. The grid comes cut into rectangular rooms, and some of those rooms carry a number. You shade cells until every numbered room holds exactly the count it is marked with. A room with no number holds as many as you like.

Two shaded cells may never sit side by side, and everything you leave open has to stay in one group. The fourth rule is the one you will not have met elsewhere: a straight run of open cells may pass through two rooms, never three. That turns a border you would otherwise read straight past into a constraint, and it is why a room's number and the room next door have to be read together.

How it plays

The difficulties

Easy is five by five, cut into eight small rooms, and a room that small usually settles on the spot. Medium is seven by seven, where the two-room run rule starts deciding cells the numbers alone leave open. Hard is eight by eight in eighteen rooms, and most boards ask you at least twice to suppose a cell one way and follow it until something breaks. Bigger was tried and dropped: a ten by ten measured out at ten minutes, well past what the tier allows. Expert keeps hard's eight by eight and takes the numbers away instead. Fourteen of the eighteen rooms are blank on a median board, and a room with no number is settled by the two-room run rule alone, which a fully numbered board never needs. A fresh board is dealt every day, for nothing.

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