The original version of Ghostbusters: The Video Game was delisted from Steam in 2017, presumably due to the licence running out. When the remastered version was released in October of last year, the PC version was only available on the Epic Games Store. Now it's about ready to end its period of exclusivity, and will be coming to Steam on November 17.
Originally released in 2009, Ghostbusters: The Video Game featured voice acting from all four of the original movie's Ghostbusters, and was co-written by Harold Ramis and Dan Aykroyd. As our Rich Stanton put it, Ghostbusters the game was the real Ghostbusters 3.
The only change to the remastered version is a title card dedicating it to the memory of Ramis, who died in 2014, and some minor visual improvements. It still has that negative mouse acceleration thing, so if you do give it a shot you're better off playing it with a controller.