Some guidelines for the design of handheld games.
“There are two major things you have to keep in mind concerning the interface and user-experience, first one is that most players will be picking up your game in short breaks. They need to be able to quickly start it, and quickly put it away without losing “everything”. The second thing is that you are dealing with alot of non-technical people, without any or little gaming experience. So keep things simple and intuitive.”
Link: Mobiles, design, and gameplay (orangepixel.net, page no longer exists)