Unlockable stage

An unlockable stage is a stage that is not available at the start of the game (unlike a starter stage), but must be unlocked. Just like an unlockable character, is required to accomplish a particular in-game feat and once complete, a message will tell him the stage is unlocked. In Super Smash Flash, there were only two unlockable stages, which were Battlefield and Final Destination, stages which have appeared in every Super Smash Bros. instalment to date as starter stages.

Super Smash Flash 2
No unlockable stages have still been confirmed since the game is still in construction. To see the stages go on Smash Flash Dojo: Stages