Enter the following at the Main Menu. You will hear a sound to confirm:

Invincible:

Up, Up, Up, Circle, Square, Up, Right, Left.

Full shield and attack power:

Triangle, Square, Triangle, Square, Square, Up, Up, Up.

All Levels:

Triangle, Square, Circle, Triangle, Square, Up, Up, Up.

Secret Room:

In the level "The Labaryth" just as you are about to go into the room to save Xena's friend take a right. There will be a series of halls. Follow them to the end. There should be some health potion and a torch on the wall. Walk through the wall into a computer lab. How would that get there?

Hints

Use the Chakram to Hit Bells:

When the bell tolls, a magical power-up should appear underneath it. There are bells in the practice level and another in "the pirate Pactolus" there may be more!