You are a saboteur
Try to be helpfull in the beginning to avoid being a suspect.
When you have a helpfull path card, try to discard it, but don't do this too much. Else you will look like a suspect.
Try to create some chaos while not revealing yourself.
Lie about your goal card if you get caught by another player and accuse this player for being a saboteur. Now block him or her.
Near the end of the game, you must sabotage. Using a rock fall card on an important tunnel is a good plan. You can also block all other players (except suspect-saboteurs). …