For example, they switched engines from Quake II to unreal, so they had to start all over.
Switching engines does NOT mean the developers had to start over. Models and even maps can be moved from engine to engine since they are usually created in apps like Max and Maya not proprietary design tools. True, the code wouldn't migrate (at least not verbatim), but that is not all there is to a game. The art and media assets are the majority component.
By the way, Joel, I like the Amp II engine, and I even like Gore multiplayer.This comment was edited on Jun 13, 19:31.