Given the reaction from fans, Metal Gear Solid 4: Guns of the Patriots might as well have been subtitled OMG Snake is Totally Old. Although we've only seen the trailer so far, Solid Snake's grizzled appearance is already drawing murmurs from the peanut gallery.
But while he's become the butt of innumerable Viagra jokes, Snake won't be softening with age. Set some years after Metal Gear Solid 2, his next adventure will take him out of the jungles and corridors he's used to, dropping him into the middle of full-on futuristic battlefields as a mercenary superspy. In these war-torn environments, he'll have to contend with soldiers from multiple factions, as well as scaled-down versions of Metal Gear that look all biomechanical and make horrible, cow-like bellowing noises. (Series creator Hideo Kojima is convinced, incidentally, that these "natural" sounds will put you at ease before the things fill you with missiles and jump up and down on your corpse.)
Kojima has mostly kept quiet on what all this will mean for gameplay, but we do know that the missions will be more complex than before. Sometimes, for example, Snake will creep into battles between two armies on behalf of a third party, either to influence the outcome or to snag some item in the confusion. Not every soldier on the battlefield is necessarily a target or even an enemy, either, and Kojima has hinted that players will be able to change the course of the story through their actions.
There are other details, too: the Close-Quarters Combat from Metal Gear Solid 3 will return, letting players easily choke, slam and otherwise mistreat their enemies, and the hunting and healing mechanics from that game could come back as well. Drivable vehicles are a possibility, and other planned features include Snake's high-tech "Solid Eye" eyepatch (which replaces his thermal goggles, radar system and other as-yet-unspecified gadgets) and the tiny, overcute Metal Gear introduced in the trailer, which will follow Snake around and possibly be controllable.