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How to play Ripple Effect (Hakyuu)

Ripple Effect, also called Hakyuu, is a number-placement puzzle. The grid is divided into rooms. Each room of size N must contain the numbers 1 to N. And if the same number appears twice in a row or column, the gap between the two copies must be at least that number of cells.

1. 1Fill each room 1 to its size. A room with N cells must contain the numbers 1 through N, each exactly once.
2. 2Keep equal numbers apart. If a number V repeats in the same row or column, there must be at least V cells between the two copies.
3. 3Start with given numbers. Use the numbers already placed to anchor each room and apply the spacing rule outward.
4. 4Place the 1s carefully. Every room has a 1, and 1s are the easiest to violate the spacing rule, so they're a great place to deduce from.
5. 5Use Notes for candidates. Pencil in possibilities per cell, then eliminate using room contents and spacing.

Tips & strategy

Big numbers are your friends: a large value can only sit far from its twin, so in a tight row or column there may be just one legal spot. Solve room by room, but always check the spacing rule against neighbouring rooms — that interaction is where Ripple Effect 'ripples'.