I love this game and I knew I would.
It took the Halo game and made it my way.
You play as an ODST (Orbital Drop Shock Trooper)
and you drop into the city of New Mombasa, the only place in the world ware the Alien Alliance known as "The Covenant" decided to attack.

*slight spoiler on this segment*
The Office of Navel Intelligence thinks the Covenant are looking for something, the same something the the A.I. superintendent known as VIRGIL found in his size mic servery.
*the main connection to Halo3*
that giant forerunner crater in that city in Halo3 is what this "thing" the Covenant are looking for...

Unlike all the other Halo games stealth IS an option.
You play as Rookie, an ODST and you've been separated from the rest of your team. You wake-up in your pod 6 hours after your drop and your begin your search for clues as to ware your teammates are at night in the Covenant occupied City of New Mombasa.

You get two upgraded and sound suppressed weapons, the M7 Sub-machine gun and the M6S Pistol which you can use these for long range to take the covenant out before they knew what the hell just hit them. You also have a VISR which will make seeing as night much easier as well was make the enemies highlighted in red, Allies Green, weapons and useful equipment blue and important things bright yellow. They also gave up a map system so we can find ware to go, locations of friends and foes and the option to place way points anywhere on the map which I use to mark good gear locations.

That was the campaign mode which can be played between 1-4 players.
Firefight is a 1-4 player Survival mode ware you get waves after infinite waves of enemies that you have to take out with a share pool of limited lives, which I find to be very fun and very hard especially with the difficulty multiplier skulls that turn on slightly randomly that can do crazy things like make the enemies love to throw grenades, regenerate stamina only if you punch an enemy, make shields absorb bullets, give them twice as much health and shields and more...
So it gets real hard real fast and I could use all the able teammates I can get.
As crazy as this may sound I already have all the achievements for it, but I love this game so much and will play it anytime anyone wants me to.

If you want a good team player in your Firefight, add me,
I'm Ravin Blackhart and I look forward to playing with you in ODST!