I tend to variously rant and rave about the casual-type games that cross my path: it’s a genre I want to love, but often don’t.
But here’s one that offers considerably more depth of game play than you might initially expect: Gabob‘s “Now Boarding”, a game about airplane routing. You own an airline and airplanes; you get to direct them where to pick up passengers, but you also get to hire and fire airline employees, decorate the terminal, and buy upgrades for your equipment.
Emily Short's Interactive Storytelling 