A collection of 200 previously unpublished Difficult Su Doku puzzles. Perfect for the more advanced Su Doku solver in need of a constant supply of challenging puzzles. Guaranteed to provide hours of absorbing, brain-stretching entertainment.
`Brilliant' Guardian `Fascinating and often delightful' The Times SHORTLISTED FOR THE 2017 ROYAL SOCIETY SCIENCE BOOK PRIZE What if intelligent life on Earth evolved not once, but twice? The octopus is the closest we will come to meeting an intelligent alien. What can we learn from the encounter?