I've actually found play to be indispensable at being the best you can be at work. Because the end result really doesn't matter, play lets you experiment more than you would otherwise. This experimentation allows you to discover possibilities that you otherwise would have been too risky. Normally this applies to playing around in the same ___domain as your work (I make stupid/playful websites to practice my web programming skills, for example.)

This is just a video game, but there are still a lot of transferable skills that are practiced: concentration, planning, forethought, logical thinking, multi-variable problem solving, persistence, etc. These habits would serve him well on a programming job, for instance.