Was playing Risk a while ago with my mates, cause we're that cool. At the start of the game you get given a random objective card that no one else can see. It could be take over all of North and South America, or wipe out the Blue player, etc. While one player builds a huge defence and looks seemly invincible, the other could be slyly completing their goal of wiping out a much weaker player. The strongest might notice that you're going out of your way to pick on a particular player and second-guess your objective. I guess the fun comes from the uncertainty. The strongest might not be winning, players can bluff what they are trying to achieve. It creates situations where suddenly a conflict with your arch rival becomes meaningless if another player is about to complete their objective.