Yen Sid's Lab is, as the name suggests, the home of the wizard Yen Sid. It is a very important location of the entire series, which contains the workshop in which Yen Sid created the Cartoon Wasteland model. As with Mickey's House, it was only shown in the first and last cutscenes of Epic Mickey (along with the comic Tales of Wasteland (particularly the "There's a hole in the sky" story), novel and graphic novel. In Epic Mickey 2: The Power of Two, however, it is a gameplay world.
In the first game, the Map Room is the only room seen from the lab, and it's only visible in the opening and ending cutscenes. This is when Yen Sid was giving the finishing touches to the model of Wasteland. The staircase leading to the Starry Cliff Tops are also seen.
In the sequel, the castle becomes a gameplay world in which Mickey has to get the Paintbrush and paint the model of Wasteland. The lab includes the Map Room, the Starry Cliff Tops, the Observatory, and the "Study Room".
Environment (Epic Mickey 2: The Power of Two)
At the entrance is the room where the Wasteland model rests. Mickey must break the glass containing Yen Sid's hat to bring the Magic Brooms to life, and to get his costume piece. When you follow the brooms upstairs, there will be a deep pit, a lock door, the mirror that you Mickey will have to go through that leads to Starry Cliff Tops, where he'll need to get his brush. There is also an entrance to a hallway to the left that the brooms will take (which is most likely the Telescope room).
Mickey will seemingly be back at his house, but thinning away the wall behind his TV will reveal that he is actually in Yen Sid's Observatory. This area features an impressively large telescope that Mickey can thin the base to form a platform, along with paintings of the Brooms and the large thinnable stained glass window. By thinning this window, you can see the Mickey constellation (if Mickey painted in all the stars and comets), or a stormy sky. The brooms are all flooding the room. Mickey has two options, use thinner to simply make them lifeless and stop them from flooding Yen Sid's castle or ignore them.If Mickey thins the brooms and paints in any missing paintings, the water on the floor will drain away revealing two treasure chests. There's also 4 large spheres showing the sun and moon, which Mickey will have to thin the bottom of and then paint it in again to create platforms in order to make his way to Yen Sid's map room.
Here is where Mickey sees a canvas showing half of a treasure chest and half of a golden E-Ticket. He must choose to either paint it in to access the chest or thin it out to reveal the Oswald E-Ticket. Whichever he does, it forms a long hallway for you to receive your prize, and the wall will then open itself to reveal that its an secret entrance back to the workshop. In this room, there are two glass stained windows, the left blue (Paint) and the right green (Thinner). There is also a medieval desk with a chair on opposite sides.
- The locked door that you see when following the brooms cannot not be opened, as Mickey would have to jump over it. There is nothing behind it, however.
- In Epic Mickey, Yen Sid's Castle is accessed through Mickey's mirror, but in the second game, it is linked through the TV in Mickey's house. It is due to the fact that Mickey's mirror can no longer reach there (because Yen Sid used the brush to change the mirror back to normal).