From the Vault — originally published August 15, 2008. Some links, videos or prices may be out of date.
Akuma, or Gouki has been unlocked in Street Fighter IV arcade machines. Akuma is not playable (at least not yet) but is a CPU controlled fighter that you get to fight if you are very good at the game. Also there is apparently a PASSWORD option in the Street Fighter IV arcade machines that lets you unlock Akuma in addition to the timed unlock so it seems that more characters may have yet to be “unlocked.”
