Twilight Princess is the very height of fantastification!!

[A Black Falcon]

As I said, the Valve guys have already stated exactly where their inspiration game from, and it was from a group in Digipen's really old demo.

A game that, I believe, dates to 2004...

ABF, that CAN be chocked up to coincidence. Magical thinking doesn't JUST apply to shamans, it also applies to conspiracy theories. Keep that in mind.

When it's that close, and the idea is so similar? It's like how Nintendo would always release a press release just before or after a major game release on some other platform if they didn't have one of their own to release -- it distracts attention from your competitors (though it must be said that despite some past words now Prey is available on Steam, though this just dates to last month...)...

You say there's "no way" it couldn't have been inspired, but there is. If they didn't hear about it, that's one right there. I for one didn't know Prey even existed until I saw it in a store. Unless you have something more substantial than an announcement "soon after" (and when else were they going to announce it? They had obviously already been working on it for some time, did you expect 10 years? Coincidence easily explains it without needing further entities), you'll need more evidence. Just let it be.

Are you really a typical PC gamer, then? You'd never heard of Prey in the decade it was in various forms of production, at a major PC developer? Erm...

Anyway, Valve is made up of PC gamers at least in part, and I'd be extremely, extremely surprised if any decent group of PC gamers had no knowledge of what 3DRealms had/was trying to do with Prey. Sorry, but it's just an impossible proposition.

... and anyway, rumors of Human Head making a Prey game go back several years... I remember reading a rumor about that like a year before the thing was actually announced.

Also...

Prey: released 7/11/2006.
Portal: announced 7/18/2006. One week later. That's "near", to say the least, and well beyond the margin for any cooincidences.

Look... if Valve wants to use portals, sure, they can. But don't try to pretend that they're being original with it...