So I highly enjoyed Prey back when I played it, but I had to turn down most of the effects and whatnot to get it to run smoothly, which was fine. If Prey 2 is running on the same engine, does that mean I'll be able to run it, or will they mess it up by requiring a more modern gfx card?

We don't know what the system requirements will be.

On one hand Prey is six years old, and a computer that had problems back then may not be well-suited for a new release. On the other hand Prey was released on the XBox 360, as will Prey 2 - the recommended system requirements will likely go up but perhaps you'll still fall within the acceptable threshold.

(Note: mods are volunteers, not Bethesda employees. We do not have any insider information nor should our personal speculation be taken as official in any way, shape, or form. Until the official system requirements are released questions like this can't be properly answered.)

well i think if you look at bs recent games particularly skyrim. they had pretty good graphics and the looked beatiful i would expect the same of prey 2 at least im hopping for the same so i do not think a six year old computer would be able to handle it however i have been proven wrong in hte past. but if it was me i would not hold my breath.

Prey 2 is being developed by a different studio using a different engine, so I'd take the comparison to BGS's games with a grain of salt. Still, Oblivion and Prey were both released in 2006 on the PC and XBox 360, and Skyrim and Prey 2 are both using engines similar to their predecessors and maintain support current generation consoles. In the case of BGS's games the PC requirements have crept up a bit: here are the minimum and recommended requirements for http://www.uesp.net/wiki/Oblivion:System_Requirements, http://www.bethblog.com/2008/10/09/pc-system-requirements-for-fallout-3/, and http://www.bethblog.com/2011/10/25/skyrim-system-requirements-announced/.

While there has been some creep it isn't drastic, but a computer that could just barely play Oblivion probably couldn't run Skyrim. This being said, I can play Skyrim quite smoothly on my five year old desktop, and my wife is managing comfortably on a vanilla laptop that's nearly as old (although NPC fade in closer than she'd like).

But as I mentioned before this is a matter that really can only be settled with the official requirements are released. I will add that Prey and Prey 2 are both using id tech 4 as their base but we don't know the amount of customization that's going in to the sequel.