9. Pandemic ($6.99)
In this popular game, players try to save the world from certain doom at the hands of killer diseases. The iOS port brings save-the-world-or-die tension to your phone, and even lets you play with up to three friends in pass-and-play mode. It has easy instructions and a tutorial so it is very easy to play. Pick from one of the available roles (Scientist, Researcher, Dispatcher, and others) and get to work saving the world!