DKM Hitori an elegant logic puzzle with very simple rules. The puzzle starts with a grid full of numbers and you need to detemine which numbers to "black out" so that there are no duplicate numbers in any row or column.
There are only two rules determining which numbers may be blacked out:
1) No two black cells may be adjacent either horizontally or vertically.
2) The remaining (non-black) cells must join together to form a single area. In other words, you must be able to move from any non-black cell to another non-black cell moving only horizontally and vertically.
There is a new puzzle each day for each difficulty level for each of the four grid sizes.
All puzzles are solvable by pure logic alone - no guessing required.