Anyhow, today that all changes as I’ve come up with something that is (a) original to the best of my knowledge and (b) isn’t totally lame. I call it Sudoku Islands. The idea is basically a hybrid of sudoku and nurikabe. You have an NxN grid, and the idea is to fill in each column, row and box with the digits 1-M, where M < N. Moreover these digits form a connected region of the grid, with no 2×2 blocks, which surround islands. The size of these islands is clued by the grey squares, and there is exactly one given clue per island in the solution. Unfortunately if you are used to nurikabe much, the roles of white and grey (black) squares have become reversed, but you’re playing by my rules now so I guess that’s hard cheese!
What you get is in my mind something that works out to be an improved version of extra space sudoku, where you not only have to fill in the grid, but also have to work out where the extra space is. That’s all beginning to sound a bit wordy, so here’s a really easy toy example for you to get the idea. Fill this grid with digits 1-4 in each row/column/box:
#068 Sudoku Islands – rated very easyAnd this one with digits 1-5. Enjoy!
#069 Sudoku Islands – rated mediumAll puzzles © Tom Collyer 2009-10