Master Chief returns for game number 3, and my god, is it good!
In Halo 3, Master Chief is still sporting the Mark VI armor (Thankfully?).
You start off exactly where you left off in Halo 2. The starter of the first mission eases you back into the Halo controls and gameplay, it also gives you chance to try out the new equipment and weapons (If you haven't done so in the Beta already). It's the typical Halo story to start. Everything's going fine, your hiking through a forest when suddenly 'Oh no, someone's been captured!' Detour insues and you shoot a bunch of grunts and brutes. Also this time you have The Arbiter on your side, he sports a Carbine and Energy Sword (though he only uses the sword in cutscenes, wierd huh?)
The new weapons and equipment are pretty standard, there's the spiker, which is basically the brute version of a plasma rifle, then there's the power drain and bubble shield (You may have seen this in the Beta) which don't add much to the campaign but make the multiplayer a lot more interesting.
Also there are two new grenades, there's the spike grenade, which sticks to enemy like the plasma, but sends deadly spikes in one direction, this is fatal when stuck to someone. And the fire grenade, which is basically a petrol bomb.
The multiplayer is where the game really expands, there's matchmaking, custom games or even co-op campaign online. The devs have kept the multiplayer feel from Halo 2 and the heroic map pack have breathed life into the game also.
Forge is a new addition here as well, It lets you as add and subtract weapons from maps already available, there's no terrain editing, but a clever forger on The Foundry will be able to terrain no problem.
There's also theater mode, which to be honest is a pretty pointless addition but it's there nonetheless and some may find it useful.
Overall, Halo 3 is much like it's predessessors, epic, violent and brilliant. I'd recommend it to any gamer and anyone.