there is a code you can get from somebody!
you have to finish the puzzle then click on the door
you do the puzzle
No
You go through the puzzle door and beat Mordred. (see two related questions)
Into the castle. To follow him, you have to solve the puzzle door. (see the related question)
Solve the door puzzle and battle Mordred to save the (real) Princess. (see related questions)
find a way to
Solve the door puzzle (he's Mordred) and battle his robot warrior suit. (see related questions)
You can click on the door behind "her", but if you give her the weapons, you have to solve the door puzzle to enter the final battle against Mordred. (see the related question for the solution)
the door that's locked
On the secret planetoid (X11 Y82), you can draw the Golden Key from the crystal, opening the path to the castle in a far galaxy. To enter, you will have to solve the door puzzle by the Binary Bard. (see related question)
just click randomly