Seen here: Presentation: Series 40 Game Usability Study at Nokia. It is a presentation of the results of a game usability study, coordinated by Nokia and conducted by Idean Research Ltd., a Finnish user experience research firm. The study concentrated on solving usability and playability issues in games developed for Series 40 devices from Nokia.
1. Provide a Clear Menu Structure Use only one main menu, accessible with the left soft key. Keep the menu short. In general, use the left soft key for OK, select, and menu; use the right soft key for cancel and back. 2. Simplicity Is Key If two solutions are equally valid, use the simpler. Make sure each entity in the game is unique, and not easily confused with any other. Provide different game modes only if they are truly different and valuable. 3. Provide Help When Needed Keep help text short. If feasible, scroll text one screen at a time, not one line at a time. Display short text on the screen to explain new items, characters, and situations in the game. Provide a setting to disable in-game help. Provide a graphic representation of which keys are used for which functions. Do not expect players to read help text or force them to do so. 4. Be Relentlessly Consistent Use the mother tongue of the user. Be consistent with the phone's UI, with game industry conventions, and within the game itself. Use the left soft key for OK, select, and menu; use the right soft key for cancel and back. 5. Don't Waste the User's Time Allow her to skip the introduction. Do not require re-entry of data. Provide shortcuts and reasonable default values. 6. Use Natural Controls Use the 2, 4, 6, and 8 keys for horizontal and vertical movement as well as the arrow keys; use the 1, 3, 7, and 9 keys for diagonal movement, if enabled. Use the 5 key as the action button. Design the game so that it does not lure the user into pressing two keys at once, since many mobile devices (and all Series 40 devices) do not support simultaneous keypresses. 7. Enable Save and Pause Provide a simple save-game feature. Have the game auto-save when the user presses the red phone button - use the destroyApp() method to do this. Provide a pause mode (left soft key, which goes to the game menu); this can be done using the hideNotify() method. If the user quits the game from the pause mode, have the game auto-save. 8. Conform to Real-World Expectations For example, when jumping or throwing objects, the flight path should be predictable. There must be no invisible barriers that the player cannot pass or holes that he cannot reach. Do not end the game arbitrarily. Implement a realistic physics model if relevant (for example, racing games). 9. Go Easy on the Sound Provide sound for feedback, but ensure that the game is playable with the sound off, and provide an easy way to turn sound off within the game. No annoying sounds: not too loud, not too high-pitched. Avoid background music, if possible. 10. Implement a High Scores List Tell the user what score he reached before asking for a name; provide the previously entered name as the default. Do not force the user to enter a name; make it optional.