The Halo 3 Beta walkthrough

Snowbound

A large open map that features two structures connected by a network of tunnels. To have a chance on this map you'll need to be able to use mid-range weapons like the Battle Rifle, Carbine and Spartan Laser like a Jedi uses the Force. You will get sniped - a lot - so don't go wandering around in the open. And zooming around in the Ghost will only make you an easy target for the Spartan Laser.

There are plenty of grenades lying around so make sure you use them. Killing from the grave is half the game these days...

An Invisibility pick-up hides in a small underground passage not connected to the tunneled-network. The shotgun is what you need here for close range battles in the tunnels, though the new and improved assault rifle goes a long way in Halo 3. You'll also find the Brute Shot sitting on top of the large gray tunnel entrance.