Can you be the joker in Batman arkam asylum?

In Batman Arkham Asylum on ps3 you can actually be the joker! You must unlock the mission in which you can be joker and play it in the Challenge Mode. You have to progress through the game to unlock the mission and finish some riddler missions.

If you are logged in you may be able to succesfully do challenge Missions, Sometimes you have to download to the latest ps3 version, and you may also do other Challenge Missions in the Challenge Mode.