Some of the core people behind the first game were fired. They say it's because the owners of the IP were doing something malicious and wanted them out of the way. The company says it's because the main guy (Kurvitz) was impossible to work with and couldn't behave. There are interviews with people who worked with them on the game and it does seem like it was a very toxic environment (that nevertheless produced a masterpiece). It's hard to tell what's really going on.

It's a shame because Kurvitz was behind most of the crazy ideas in the game but I can also understand if people don't want to work with him again. It's also very possible that some dodgy dealings are going on with the ownership of the IP like he claims, but that's not really clear.