I tend to gravitate toward Streets of Rage Remake; It's a fan-made Streets of Rage game (combines ALL 3 games in a choose-you-own-adventure style of game. Every track from the trilogy has been remixed. It has multiple endings and tons of secrets to unlock (and buy with your in-game currency). It's short, simple (yet complicated), has good music, and is fun to chill out to.
That and The Typing of the Dead. I get to up my typing skills and get to enjoy the awesome voice acting (haha).