For decades, the majority of video games have been about non-stop action, encouraging players to stop on innocent turtles, shoot terrorists and generally go nuts. Sure, there's the odd strategy or puzzle game, but even those have an element of tension and urgency - it's part of what makes them fun. Game developers know how to push our mental buttons of risk and reward.
But in the last few years, we've seen a genre of games that stress just the opposite, relying on slow, measured gameplay that's relaxing rather than exciting, soothing rather than stressful. They rely on simple, colorful visuals and gameplay that bucks the trend of traditional game theory.