Big Huge Games lead designer Ian Frazier said the finished game is "in much better shape" than the demo, which was not created by Big Huge Games.
"There's a lot of tension about the demo, which we didn't build in-house," Frazier told Eurogamer. "It was branched off our code about three months ago. It got a lot of bug fixing. We sent them what we had, but there are a lot of bug fixes they didn't get. So we're all nervous, like, the demo's really buggy.
"But all the time the demo was worked on is time we spent de-bugging the main game. It should be clear from the reviews the main game is in way better shape. That's been a source of nervousness."
"I'm not going to say the game's bug free - no game is. But it's pretty darn solid. Final code will show it's way better across all three platforms than the demo build. The demo didn't see the advantages of the last home stretch of bug fixing, which is a little bit painful."
In fact, the demo introduced bugs into the game that never existed in the code Big Huge Games created.
One of these relates to dialogue skipping - the result of missing voice over in the demo.
"The thing that's really hurtful for us is they actually introduced some new bugs in the demo that weren't even in the game when it branched," Frazier said.
Dialogue skipping is "not technically a bug", Frazier explained. "What they're seeing is the VO just isn't there. The big challenge for this demo was the game is frickin' huge so trying to get the download size down to something reasonable was a real challenge for the group that was working on it.