- Screen size and resolution
- Available space for application and storage
- Processing power
- Form Factor
- Use cases (where will the game be played - what external factors will be in play)
- Colour and Sound support
- The thing might ring at any time!
- The phone has characteristics that many PCs and consoles don't - Camera, Address Book, SMS/BT/WiFi/GPRS/3G, Location awareness
- The phone's always with you (one of 4 things you "always carry" - Wallet, Keys, Watch and Phone)
- Allow play in short, interruptible chunks. The game doesn't have to be finished in a short time. it just has to be possible to stop pretty much any time and start again from there later
- Game play should generally be slower than mainstream PS/Console games
- Games should work both on and off line.
- Mobile phones are social devices - at a party for example, everyone's likely to have one
- Game play should be simple (like Sudoku) but not simplistic (like Tic-Tac-Toe)

One really interesting idea presented at the end was of different devices connecting to the same game server and providing a different experience for the same game. The example given was an online FPS where a mate of yours needs help in a situation and he contacts you. You're off-line but you've got your phone. You connect to the server via the mobile and you're presented with, perhaps, a scope view only so you can do some sniping. We've been talking about this for some time in enterprise apps, but I, at least, hadn't made the leap to gaming. Very cool.