The only word I can say for this game is "magnificent!" I can't quite put my finger on what makes this game better than any other first-person shooter i've played, but I do know that it's the only one I like enough to purchase. The story is given in other reviews; basically, humans are fighting a losing war against a covenant of aliens bent on eradicating us called (surprisingly) the Covenant. You play the last remaning supersoldier called Master Chief, and you're on a last-ditch mission to draw the alien forces away from Earth. The ship you're on makes a random space jump and crashes on this place called Halo. It seems to be a planet...or is it? What secrets does it hold, why are the Covenant exploring it? Play the game and find out.This is an intelligent gamer's FPS. You have limits as to what weapons you can carry (2 at a given time) and you can only pick up ammo for the weapons you're carrying. You can only have 4 grenades (thought you can have 4 each of Marine and Covenant grenades, switching to the one when you run out of the other), and you have control of various vehicles at various points in the game. You also have the intermittent support(?) of Marines who crashed with you. Usually, they end up being cannon fodder, but they can hold their own; if you're in a Warthog (indestructible 4WD that holds you and two others), it's great to have them as gunners.
My passion is the weapons. These are for your selection, human first then Covenant
Assault Rifle: The mainstay of your armory (in my opinion), I view this as a steady girlfriend. You may date others and use them more, but you always return to her. It is good allround, has a max of 600 bullets with a 60 bullet clip. Relatively accurate but don't try sniping with it. I always try to have it as a backup. I may use the shotgun or plasma rifle as my main weapon, but this is always there.
Hand Pistol: This pistol is good for accurate shooting and taking out Hunters in their weak spots, but i haven't developed the skill for that. Other than that, I see no use for it unless you have no other weapons. It has 60(?) bullets and is a single shooter.
Shotgun: Can't dodge buckshot! This is my fav weapon in the game. It has a max ammo load of 60 shells and chambers 8. It isn't good at distances, but one shot at close range will take out any bad guy except a Hunter and maybe an Elite with shielding (and 2 shots will take the Elite out). Especially good for fighting the Flood...
Rocket Launcher: Tried and true staple of all FPS, operates like all the others. You're only allowed a max of 4 rockets, and 2 per chamber, so aim well or die.
Sniper Rifle: Great zoom, nice accurate bullets, one shot one kill, great for the game, bad for multi-players. A pox on all those who win by sniping. I believe it's a 20 bullet limit there.
Covenant weapons: Whenever possible, I recommend using these against the covenant. They seem to be more sucseptible to these than to human weapons (not that human weapons are BAD) and you can conserve your ammo better. Keep your machine gun, but use and discard Covenant guns as your main attack when dealing with covenant.
Plasma Pistol: Small energy-blast weapon that can be retrieved from bodies of defeated Covenant. It's better than fighting bare-handed, and you can charge the pistol to deliver a large burst against your enemy. Firing the weapon depletes the charge, and you cannot recharge it; once it's depleted you'll have to toss it and get something else.
Plasma Rifle: The covenant equivalent of your assault rifle, it's bigger and more powerful than the plasma pistol. It doesn't do the charge-release attack like the pistol, and must be fired in moderation lest it overheats. A good primary weapon when facing the Covenant. As its smaller cousin, it depletes with firing and cannot be recharged.
Needler: This weapon fires needles which home into and stick onto your targets, and then explodes. The needles bounce off shields and Hunter armor, but it's a decent weapon overall. You can get ammunition for it. You can have a max of 80 needles, and the weapon holds 20.
more can be said, but look it up yourself. This is a good game and I recomemnd it wholeheartedly.