OK, for examle person A starts with deviation (the starter word), person B could then go on to say octopus (which, as far as I know is completely unconnected to deviation).
However, the other players can challenge person B by saying something like: "No, actually deviation is linked to octopus because..." in which which case the challenger gets some points and also gets to suggest the next word.(if there are no succesful challenges then the person who suggests the word gets a point and the first player to suggest the next word gets it.
The point system goes something like this:
15 for reaching the starter word
2 for a successful challenge
2 for a word with no successful challenges

Open to any suggestions to make this game more workable...