Fallout

I honestly disagree a bit with that. 1 was a dark comedy, 2 was half dark comedy half absurd references, 3 was bleak absurdism, New Vegas was back to dark comedy, then 4 went to less dark absurdism.

In general, the classics and New Vegas better carried the serious tone, while 4 was pretty close to pure parody. Like 2, 3 seems split in half, while 1, NV, and 4 were more consistent in tone, though not necessarily with each other.