Covenant Forces are attacking Earth the last Human Planet.  Master Chief arrives in Longsword Fighter above Earth and dives out on to Covenant Battle Cruiser.

 

Planets:

 

Covenant Homeworld (maybe)

Threshold (you know the planet Halo orbits)

Earth

A Moon

Another Halo (or else why would they call it Halo 2?)

 

New Covenant:

 

Prophets

Brutes

 

New Vehicles:

 

ATV

Modded Warthogs

Spectre (Covenant Bus)

Phantom (Cov. Dropship)

 

New Weapons:

 

Battle Rifle

SMG

Flamethrower (possibility)

Energy Sword (possibility)

Fuel Rod Gun (c'mon even Grunts use them!)

Remote Grenades

 

Extras:

 

New and Improved Marines

Shadows for sneaking

Tables for cover

The ability to run

Kick people out of moving vehicles

Look around corners

Double 1-handed weapons!!!

Guilty Spark (Monitor)

The Flood (yes that's what I said.)

 

Oh and Sarge is back!