Riddler Making Appearance in Batman: Arkham City
In Batman: Arkham Asylum Edward Nigma just left some riddles laying around to be discovered.
However, in Arkham City,The Riddler will be taking on a bigger role. His puzzles will be back, but will have more of an effect now.
Instead of just trying to solve riddles in your spare time, The Riddler will now hold Gotham citizens hostage, killing them if you fail. Seems like a pretty big change from the last game.