The second act of the Halo saga picks up right where the first one ends -- in a scattered debris field left by the destruction of the Halo. There are big things afoot, as we witness the trial of the Covenant fleet commander responsible for the Covenant's failure at Halo.
After the cutscene, you start in the armory of the Cairo Orbital defense platform. This whole sequence is just like Halo 1. Look at the lights, charge your shield, and some witty NPC banter. Here's your first chance to move the Chief. It's like putting on an old jacket -- it feels good to be back. Take a minute to move around the armory, and you'll quickly discover something new in "Halo 2": interactive environments. Cans, chairs and other objects can be moved around or knocked over much to the chagrin of the gunnery sergeant.
After a brief walk with Sgt. Johnson, another cutscene begins and the Chief attends a meeting of the Navy Brass. In a great cinematic cut scene, the story moves forward along two lines: the awards ceremony of Master Chief and the punishment of the Covenant fleet commander. The party is short, as the newly coifed Cortana picks up Covenant attack forces on her sensors. The Covenant is at our doorstep!
The action starts quickly, as Master Chief sets out to repel boarders attacking one of the orbital defense platforms protecting Earth. The first level is highly reminiscent of the Pillar of Autumn board from the first game. Familiar warning claxons and commands are issued over the PA. This is a nice touch as it eases the player into what is very quickly going to become a different Halo than you are used to. The Chief and the Marines battle back a sub-par Covenant attack force. This gives you the chance to figure out some of your new digs.
Dual wielding immediately comes into play. This is a great new feature that feels very intuitive. To dual wield, you stand over a one handed weapon and press the Y button. Once you are armed the right trigger fires the gun in your right hand, left trigger for the left hand. You drop the second weapon by pressing Y. The only problem I have is wanting to throw a grenade and forgetting I have to drop my second weapon to do it. This is something that will take a minute to get used to.
Chief's standard issue weaponry has also changed. The pistol and Assault Rifle have been replaced by the Battle Rifle and SMG. For me, the battle rifle was love at first sight. It has a scope like the pistol but fires accurate three round bursts. The SMG seems like a much more controllable version of the assault rifle.