I was thinking of having some puzzles, quizzes or interactive games. You can start and restart the applet by shift-clicking on the pattern. Three switches outside a windowless room are connected to three light bulbs inside the room.
Crossword puzzles provide a stimulating challenge.
Click on any letter to move to that word. The spacebar switches between across and down, pivoting around the current letter. Backspace erases the current letter. Incorrect letters are drawn in red.