Not to dominate this thread (I am really hoping there are some IF text adventures I'm not familiar with, or maybe some Japanese stuff, or late 80s DOS/Amiga titles), but for anyone interested there is also the colossal failure/letdown that was Too Human for the 360, though I believe it is nearly impossible to find as unsold copies were destroyed after a failed lawsuit with Epic Games. Conceptually, Too Human is Norse mythology with posthumans in place of the demigods and robuts substituting for, uh Loki's minions I guess? It is alluded to that the Ice Giants (Ymir) were AI that the Aesir posthumans defeated, and if this all sounds pretty awesome it is, at least in theory, but the game itself was painfully repetitive, I think there are only two enemy types in the whole game, which isn't even very long. The suggestion of greatness was there, and this was intended to be the first of a trilogy (and the cliffhanger ending would have gotten me to buy the sequel had it ever been released, despite my disappointment), but the game sold very poorly, the developer sadly went out of business (Silicon Knights, some might know them as the dev of Eternal Darkness, one of the best non-Lovecraft Lovecraftian games, on Gamecube), and they lost a lawsuit against the 3d engine designer over claims of breach of contract.
Anyway, Too Human is probably the closest I've ever seen a game come to that traditional transhuman setting, even if it was a kind of insane re-imagining of Norse mythology.
Played/Slogged through this game a few years after it came out. Loved the ARG content surrounding it (Eg. Mockumentaries about "relics" recovered from the ice and display at the Ontario Expo... Woot! Go Canada!) And just the fact that it was made by a company so close to home. It had so much potential but as it was stated the gameplay faltered in execution. I remember getting to that ending after a few good...? hours cutting through and being cut down by hordes of robotic goblins and dark elves and then just dropping the controller at the cliffhanger... it could have been soo good!
Also would "Enslaved" be counted as Trans-human/Post-human? It had a very strong similar vibe as "Too Human" except using "Journey to the West" in place of Norse Myth.