But that's just the plot. There's another side to this story, and it's the one told by the game's locations, action and dramatic high-points - and in some cases, by moments between its handsome, expressive and earnestly-voiced cast of virtual actors. This story is, by contrast, a richly satisfying success. Tune out the details, and Guns of the Patriots is a properly gripping yarn, full of thrills, spectacle, laughs, and even tenderness and pathos. You won't understand, but you will care.
Design-wise, MGS4 is mostly a refinement of what's gone before. The new gadgets are superb, the weapons are expertly realised and much easier to get hold of, and there are always plenty of options, even if stealth is still usually the best of them. Hand-to-hand combat feels more natural. The environments are more complex, but nothing like as large or open as you might expect, and this is still a linear game.
Only the new Stress and Psyche meters don't really gel with the flow of play; we suspect they come into their own in the highest difficulty settings, but at that level, Metal Gear Solid 4 is an exercise in teeth-grinding masochism for specialists only. Metal Gear Solid has always been either too easy or too hard, and too possible to get through by sloppy cheating or simple attrition, and that hasn't changed.
The first act is a tense infiltration of a war-torn Middle Eastern city, terrorised by the creepy Gekko biomechs and Liquid's personal guard, the sinister Frogs. The new enemies are great fun to gun down and outwit, and the sense of being part of a live battle-zone with several factions in play - as opposed to playing lone wolf against the guards - adds terrific atmosphere to the Metal Gear experience, even if it doesn't exactly revolutionise it.
It's everything you've seen, heard about and expected from Metal Gear Solid 4. The relatively weak second act is more of the same in a much less compelling setting - a rather unconvincing, blandly designed South American backwater - and ennui starts to set in. This is a much more accessible game to play than the convoluted MGS3, with the OctoCamo suit and Metal Gear Mk II remote drone taking much of the pain out of stealth, while weapons trading and customisation, and the excellent new cameras, do the same for gunplay. A good thing, certainly, but it lays the decade-old gameplay systems bare, with only modest improvements in AI to make up for it.
Halfway through this section, a novel gameplay idea, a rousing on-rails shoot-out, and some thunderous cut-scene entertainment succeed in sustaining interest until the next episode. It's at this point that Kojima pulls the rug from under your feet. The MGS4 you were expecting, it turns out, is no more than half of the game you get.
We're not going to explain how, because everything that follows deserves not to be spoiled - not the plot, but the string of ideas that break Metal Gear Solid down and rebuild it, in several brilliant and surprising ways, before the game is done. The first of these is such a precise and enthralling distillation and of stealth gaming that it's a shame more people won't see it, but it's worth saving for the way it takes you unawares. Each time, atmospherics, graphics, tone and gameplay revisions mesh perfectly down to the tiniest detail, as Kojima Productions bombards you with references and mood-swings that leave your head in a spin. 1940s 'noir' cinema, the Iraq war, beat-'em-ups, Halo... take your pick.