He did have this "Karma's a b*tch" outlook though. Promising one thing and then doing another, frequently just to f*** with whomever he could. I mean first he wants money, then he burns it, and kills all his associates just because. It would still be funny if the citizens decided to blow up the inmates, and accidentally killed themselves. Then when the inmates got to shore (presuming Joker doesn't kill them too), everyone thinks the city has gone mad - or the same would work vice versa. I believe the people on shore were aware of "the game". It also falls in line with his point about chaos and plans. You're planning to detonate the other ship and save yourselves, but in your selfish desire to protect your own life you actually end it. Hahahahahaha. So to speak.