Found another big one. I swear I'm not breaking the game on purpose... mostly :P
-- Going into the dungeon full of demons and coming back out again reset the entire world. Meaning any and all changes the player did to it were removed. Like, say, building a 2-story house and filling it with stuff...... But possibly even more serious, all the waypoints and places of interest had to be discovered again, and all of them rewarded me with even more skill points and exp. A massive exploit just waiting to happen. heh