The Nintendo DS is a beautiful piece of hardware. Sleek, compact and durable, it's the perfect portable gaming device. Smartly, Nintendo built in an instant sleep mode whereby you can pause any game indefinitely just by closing it.
This is a nice feature for those on the go, but in the hands of the right developer it can be utilized to enhance the player's gaming experience.
I was surprised and delighted the first time I closed up my DS while I was playing New Super Mario Bros. Suddenly, Mario himself bid me goodbye through the built in speakers. And it didn't stop there. When I later reopened my DS he announced himself to me.
Take a listen for yourself: