During a press event in Stockholm today, executive producer Brendan Goss from Terminal Reality, shared a story about the dealings they had with the actors from the previous Ghostbusters movies. Of course with Dan Aykroyd and Harold Ramis writing the script they had half the team sown up. Bill Murray is a very busy man, but the his main demand on the game was that it featured all of the Ghostbusters including Ernie Hudson and that they were given equal screen time. He did not want it to be Peter Venkman - the game.
Another old Ghostbusters star, Sigourney Weaver was approached early on about the possibility of her reprising the role as Dana Barrett. The actress turned it down, but Brendan Goss revealed that once Bill Murray's participation was made official she came back asking if she could be in the game (through her agent we presume). However, at that stage another leading lady had already been written into the story and the production was way too far along to include Sigourney Weaver's character.