At some point while on the Red Rock Town mars colony, you'll use IRIS to control a small robot. With it, you'll be able to enter a small hole just near the spot you found it. Inside you'll notice three posters which are front covers from three different games made by LucasArts. Furthermore, you'll have to pass a room where only that robot can enter, and that room will seem like a huge game store. All over the shelves will be game boxes and all over the walls game posters. You can clearly recognize Outlaws, Grim Fandango, The Curse of Monkey Island, and Escape from Monkey Island games there.