Simply put, Black Ops 2's is a more lethal strain of combat. This was foreshadowed in the debut trailer (and that advert that seems to play every time you come within a mile of a radio), in which Sgt Woods spat out something about 'machines getting stronger, while we got weaker'. And so it proves in the heat of battle.
Remember the cumbersome tanks of World War II? If they got a clear line of sight on you you were as good as dead, but you could easily outmaneuver them on foot. Well, the 21st Century equivalent are small, box-shaped robots no larger than a waste paper bin, and they'll merrily give chase if they spot you passing. We should just be thankful that their lights are colour-coded green and red, so we know who's on our side and who isn't. It's reassuring to know that such gentlemen's agreements are upheld during war, even when the fate of the world is at stake.
The rank and file weapons have also been subject to a hefty upgrade. Holographic attachments allow users to see through walls, target finders allow for auto-aiming and enhanced sniper rifles allow for five levels of penetration (not in that way, please). While the advanced tech makes it easier to snuff out enemies, it's a case of 'what's good for the goose is good for the gander' - it only takes a few shots to drop you on the floor. too.
With that in mind, perhaps the intrusive blurring effect that occurs when you take a hit wasn't the wisest design choice. On Veteran and Hardened settings, situations can go from 'hunky-dory' to 'total write-off' with just a second's lapse in concentration. With your vision impaired it's not always possible to salvage a situation when perhaps you feel you might. Couple that with some erratic checkpointing - possibly amongst the worst in the series, actually - and you've got a game that is prone to delivering the occasional bout of frustration.
We don't want to give the impression that Call of Duty: Black Ops II is a complete reinvention of the formula, because it isn't - it's still the same slicky-produced shooting gallery it's always been, rife with carefully-managed set-pieces and tight level layouts that rarely open out wide enough to offer meaningful strategic choice. But what it does do is provide the base experience with a new set of scenarios and toys to play with, and the sci-fi bent proves enough to keep the formula feeling fresh.
But although Black Ops 2 looks to the future, it often finds itself incapable of escaping Call of Duty's past. The entire first half of the game is dragged down by clumsy storytelling and an over-reliance on cheap shocks to maintain the player's interest.
In fact, Black Ops 2 sets its stall out right from the opening bell - the first thing you see is a man burning to death in an upturned truck, while you futilely attempt to stove the windscreen in with a shovel. Then you're whisked off to mow down a wave of machete-welding Angolan soldiers. Needlessly confrontational imagery is spliced with unconvincing stealth as Black Ops 2 makes an early fumble for its own 'No Russian' or Pripyat. It doesn't manage to find either, doesn't even manage to come close. But when Black Ops II settles down and begins to fight its own battles, it emerges victorious more often than not.
Black Ops 2's story is one of loss and culpability, and it exists within a branching framework that allows the player to properly engage with those themes once all the pieces are firmly in place. The first half of the game divides its attentions between three story threads - of the fate of the original Black Ops 1 team, of the tortured history of the game's antagonist Raul Menendez, and of the current (well, future) day SEAL commander David Mason, who's out to avenge the death of his father. It takes a while for the plot to tie up the past, but once it's free to concentrate on the future, it hunkersdown and delivers some of its best and most focused action, both in terms of the story and the warfare itself.
One thing you'll pick up from the early exposition is that all of the 'good guys' are inherently unlikeable, even by Call of Duty standards. It's hard to imagine this hasn't been done on purpose, since Treyarch has gone to great lengths to humanise the game's baddie, Raul Menendez. He is a terrorist, yes, but one with a tortured past that wasn't of his own making. In one memorable (if bizarre) level, you even get to play as Menendez, and given the circumstances around him, it's difficult to read his actions in this section as being anything less than heroic.
While the script may be flawed and some of the events might not hold up to closer scrutiny, on the whole it does a good job of painting a picture of the ambiguities of war, and that it does it in a way that won't upset the sensibilities of some of the more, ahem, patriotic Americans is doubly impressive. And it's important that Black Ops II plants those seeds of doubts in the player's mind, because on more than one occasion the storytellers hand the pen to the player and say "Here. You decide what happens next".