Nope. Ghostbusters the game is NOT Ghostbusters 3. It shouldn't count as GB 3... all I know is that before the video game idea came about, there was to be a CGI animated DTV with the original cast of the first 2 films doing the voice overs... sort of like the H-boy cartoon DVD's that came out in between the 2 movies, or those Watchmen DVD's that just came out. From my understanding, the DTV never made it because none of the cast could agree on mutual terms... so they basically used the same plot as a video game.But Ghostbusters 3 is coming ... as a video game, but that's the best we're getting.
If that did count as a real sequel, then Roger Rabbit 2 would technically be this old Amiga game...