Combination: automated generation of puzzles with constraints

Constraint Programming offers a powerful means of solving a wide variety of combinatorial problems. We have used this powerful paradigm to create a successful computer game called Combination. Combination is an application for the iPhone and iPod touch. It has been on sale internationally through the iTunes store since December, 2008 and received a number of positive reviews. In this paper we explain how all the levels of Combination were generated, checked for correctness and rated for difficulty completely automatically through the use of constraints. We go on to evaluate this method of creation with the use of a human evaluation. This showed that fun, immersing computer games can be created with constraint programming.