First -- you probably shouldn't bother. While there are ways to prevent this kind of "cheating," if someone wants to cheat your game, they're likely going to find a way. Either that or you will spend days and weeksn just trying to build anti-cheating into the game while you could have been writing a nice story.
However, if you want a little of this prevention, you can set all the variables instead of one. In other words, if you're giving someone one point in fighting for following a certain link and one point in hiding for following a different link, you could, for each link, set the other value to zero. In other words, when they select fighting, give them a point in fighting and zero in everything else.
