witcher was built using a heavily (in house) modded version of the aurora engine that took years to adjust to the point of not being crap.
i know nothing about civ IV, but for what its worth gamebryo is a pretty generic engine that no one uses stock.
(http://en.wikipedia.org/wiki/Gamebryo)
Arcanum and TOEE were produced years apart on a continually improved in house engine.
gamesas signed the deal with masthead 8 months ago, i really doubt that they have done any kind of extensive mods on it so far, and none that would degrade the rendering capabilities.
*edit*
could you tell that KTOR used the quake 3 engine? guess what ... they do!
the aurora engine was built off of the Q3 engine, cant tell it now as the aurora has been reworked so much over the years, but way back in the day i instantly spotted the similarities just from the NWN adds in CGW (RIP). can't see them now as the engine has been reworked into a completely different beast, but that took years.
LOL, i'm really not trying to argue tho (just geeking out right now). just watch tho, Chris will probably log in this morning and say that they are legit and that they are from the earthrise engine and i will end up looking like an ass. but i still really think that its a different engine. hay, "OC" ..... i got something for ya right here! _|_ (^.^) _|_
"MMO-RPG" = "Mass Market Oriented - Repetitive Profit Genera"
- damned things still svcked me in ...