In this video we take a look at Archetype, which is optimized for the iPhone 4 (it scales to the full 960x640 resolution). It's a multiplayer first person shooter that allows you to play deathmatch-style games with ten players over WiFi or 3G. The controls take some getting used to with a dual joystick interface: the left joystick controls movement, and the right control aim. If you've played Halo on Xbox, it's a similar setup.
The game is available for $2.99 in the app store, which is a good deal for such a graphically impressive (and fun) game.
What's your favorite 3D game for iPhone?