you do the buttons in this order sun then the star the the solar system and then hit the middle
At the Binary Bard's secret planetoid, entering the castle requires you to flip over 20 "cards" or puzzle sections to reveal a hidden picture (and enter the castle). For the solution, see the related question.
To enter Mordred's castle, solve the door puzzle. Click once on each of the 4 cards in the second row, the two middle cards in the 3rd row, and the 4 cards in the 4th row.
No, but there is no advantage to keeping them. The Princess is a disguise, and if you are fooled, you can still enter the castle by solving the puzzle door. If you click the door, you enter the final battle immediately. (see related question)
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)
To solve Mordred's puzzle and enter the castle, press each of the four cards in the second row (once), each of the four cards in the fourth row, and the middle cards in the third row.
There is a green fuel rod insode the captured robot invader, in the castle dungeon. You can enter the rear of the cell if you threw the switch when you entered from the castle library. (see related question)
Solve the puzzle door and enter to fight Mordred's robot suit, first as Merlin then as your character. (see related question)
You can't. The switch in the castle entrance only opens the small back gate. Later you can enter that way. (see related question)
you go to a giant meteor on the left corner with a castle on it and then you enter it climb up but you need all the nights to pull the giant key thing...
Merlin cannot enter the castle during the game. You should go to the dungeon the back way, by pushing hard on the dirt wall to the tunnel.
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 robot invader is held in the castle dungeon, but there is no way to get to it. Go around and enter through the tunnel in Mordred's secret underground laboaratory. (When you enter and get the cheese, pull the switch that opens the back gate to the cell.)