Su Doku, the number game that is sweeping the world, has been adapted by the Royal Society of Chemistry into a puzzle where each square must have only one of nine elements listed at the bottom of the page. The play is exactly the same as the digit version, except that one contemplates the likes of lanthanum and cerium while one plays. Check it out at www.rsc.org/puzzle.
nature.com blogs
A 20×20 square can be decomposed into a 4×5 array of 5×4 arrays (or vice versa). Since there are 20 amino acids in the genetic code (ignoring selenocysteine and pyrrolysine) it should be possible to create genetic sudoku.
You’re actually a little behind the times. I got one of these RSC books for Xmas last year… I’m looking forward to volume 3 – the problem in volume 2 with the isomers of heptane was really quite tricky.