The game was one of the first to really try to allow players to talk to characters using natural language, and given the amount of dialogue in the game (wikipedia says 16 hrs worth) there’s probably enough there to train an AI on and enough to do voice cloning as well.
A fan game could overcome a lot of that difficulty - especially if you just changed things just enough. But you’d be losing out on the Douglas Adams inspired humor, and I’m not sure there’s someone around that can the concept justice.