To play the original Atari 2600 version of this classic game, select Info on the title screen and press C 26 times followed by Down.
At the start of the "Copan" level, go forward, jump on the 'tongues' to get to the very top platform (2 tongue jumps, then 2 ledges up), then do a running jump to the left to land on the ledge with the 2600 version scorpion. Kill the scorpion and enter the door to a ledge with another scorpion, a lock, and silver bar. Kill the scorpion, get the lock, go left to hit the wall, jump up & down till catapulted in the air. Go right while in the air and land in a small room with a colorful vortex. Enter the vortex.