History stops at worldgen, so this goes one of two ways...
Either you can set a worldgen for something insane, like the year 10,000,000, and see what still lives, or you can stop worldgen at a normal time, and play as per normal.
The first way, it's improbable that you would kill EVERYTHING, as most populations are unbounded by a need for food, and as such, it's largely a matter of out-reproducing the crap that kills them. As the crap that kills them die off, they start becoming a sort of invincible super-race that dominates the world.
Basically, this means that megabeasts get an early shot at wiping out whole civilizations, but if and when they start falling, the civilized races are only vulnerable to each other, which typically means everyone but the elves and kobolds (with their inferior tech) have a decent shot at it.
Things like wolves, meanwhile, are generally just plain unkillable, since anything that has a large population to start with, and doesn't have to have mechanics for marriage will always out-reproduce anything hunting them.
The OTHER kind of kill the world is most definitely possible... if you're willing to make it happen.
Sentient species stop having babies, so they're easier to kill. Dwarves and humans even die of old age! You can kill every living sentient being in the world if you try hard enough. The same with animal populations, it's actually possible (if unbelievably tedious) to kill every living animal (plants and fungi aren't directly killable) in the world... if you do it manually. Wild animal populations do still occasionally go up, and won't go down on their own, you have to kill them personally.
You'll know you've done it when you enter The Age Of Death. Then, you can happily have your adventurer kill him/herself, and declare that you've "Won Adventurer Mode", because killing every living being on the planet is that mode's only current objective.
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Topic: Will all worlds generated in DF die eventually? (Read 1774 times)