Once you have unlocked all the playable ending demos, use the following trick to unlock their full game counterparts. Go to Sonic The Hedgehog (either version), Sonic 2, Sonic 3, Sonic 3D Blast, Sonic Spinball, Robotnik's Mean Bean Machine, or Sonic Chaos. Keep intentionally killing Sonic until you are out of lives. The game will end, then restart at its own title screen. From there, you can start at level 1 of the game and play until the timer reaches zero.