The Puzzmo manifesto is all a good read, but the section play being health resonates with me!
Play is healthy
Play is not kid stuff, or time-wasters, or gamification. Mindlessly matching gems while you watch tv is not play. Doing light math advertised to keep your brain elastic is not play. Work cannot be magically reformulated to become play. Play is its own thing. Play is engaging and all-encompassing. Play makes you feel light and free, even when it itself is deep and complex. Play is the companion of joy.