Solid Snake aside, it's patently obvious that war does in fact change (pre-nuclear war, nuclear war, and Wasteland war really have little in common), but that's stating the obvious. It sounds badass when Ron Perlman says it, but does anyone have any interpretations of its meaning?

The best explanation I can think of is that it's a statement about human nature: No matter what happens, even if the planet gets blown to hell, people will always take up arms against each other. That's probably not the intended meaning, or at least not all of it; it is war that never changes, rather than people.

"War. War Never Changes" does indeed mean that the causes for war never changes. As Fallout 3 put it: "Since the dawn of human kind, when our ancestors first discovered the killing power of rock and bone, blood as been spilled in the name of everything: from God to justice to simple, psychotic rage."

Fallout One set the stage with it's introduction: "The Romans waged war to gather slaves and wealth. Spain built and empire from its lust for gold and territory. Hitler shaped a battered Germany into an economic superpower, but war never changes."

The technology in which we wage war does indeed change. The reasons for going to war however do not. Hence "War Never Changes." Humanity almost destroyed itself. But failed to learn from that. The new world born of the old still goes to war.