There are thirteen orbs hidden throughout Inside in secret areas. Once you have found and broken all thirteen, all thirteen bulbs will be lit up near the end of the game, and you’ll be able to unlock a special door and see the game’s alternate ending.
To locate the orbs, follow the yellow cables whenever you see them.
After breaking all thirteen, the door to the large orb near the bulbs will be open, and you can enter it and go all the way to the right to break the final one.
The second bulb will remain lit on the board, so you need to return to its location, the cornfield. In that hidden area, the lever that wouldn’t work before is now active and will play three tones depending on which direction you pull it in. You must use the lever to replicate the sequence of 14 notes heard elsewhere in the game. It does not matter where you start the sequence, as long as you continue through to have all 14 in the correct pattern.
The sequence: Left, Up, Up, Right, Left, Right, Right, Right, Up, Up, Up, Right, Left, Left
(If you started the sequence at a differently point, simply loop around and continue until you’ve played all 14.)
Once you enter the sequence correctly, the door will open. Enter the room beyond, and you’ll get to see the secret ending.
If you’re having trouble finding any of the orbs or with the final sequence, use the video guide below to help you.