Ripple Effect is a nikoli puzzle that I read about a while back on su.doko.es. The name gives you very little idea of what the puzzle is like, so here is a basic description. The puzzle consists of a grid of any size divided into polyomino sections called rooms. Each room must be filled with each of the digits from 1 to the number of squares in the room. If a digit appears more than once in any row or column, they must be separated by a number of squares equal to the digit.
The nikoli page linked to by su.doku.es doesn’t have many examples of the puzzle, so I hunted around to find some puzzles to try out. The first good set of puzzles that I found was here.
Enjoy!
