Servant of the Lake has an optional secret that is separate from the normal demo ending. You can find it before entering Aldous Vanderboom's bedroom, and it starts with a locked yellow box. The code is 728. The steps below explain where to use it and what you receive.

This page includes the hidden-code solution but does not reveal the full demo route. If you are stuck on breakfast, the alarm clock, or Aldous' morning routine, use Pixel Twelve's complete demo walkthrough instead.

Open the Servant of the Lake demo walkthrough for every required puzzle in order.

The Secret Code Is 728

Continue through the demo until you have entered the Vanderboom estate and can move between its rooms. Before you go into Aldous' bedroom, look for the darker room with a yellow box sitting on a small cabinet. A black bird can be seen through the window beside it.

  1. Select the yellow box and enter 728.
  2. Open the box and take the black bird egg.
  3. Go to the small opening in the wall where a hand appears.
  4. Give the black bird egg to the hand.
  5. Take the paper the hand gives back to you.
The entrance area of the Vanderboom estate in Servant of the Lake
The hidden box is optional, so you can still complete the normal demo without opening it. Image: Rusty Lake.

The paper is the reward for finishing the secret. Keep a screenshot of it if you want to compare it with the full game after release. Rusty Lake has confirmed that a secret is hidden in the demo and mobile Lite version, but it has not publicly explained every future use for the paper.

Where 728 Comes From

The three numbers were placed in promotional footage rather than written next to the box. One shot shows a clock pointing to seven. Another uses two raised fingers in a portrait clue. A separate shot hides an eight near the maid and the floor. Put the numbers together in that order and you get 728.

You do not need to find those trailer shots before opening the box. They explain the answer, but the game accepts 728 even if you learned it from this guide. Rusty Lake's official site gives a smaller hint by telling players to follow the bird.

A room inside the Vanderboom estate in Servant of the Lake
Portraits, clocks, and small details are often used as puzzle clues around the estate. Image: Rusty Lake.

Can You Miss the Secret?

Yes. The yellow box is not required for the regular demo route. If you enter Aldous' room and finish his routine without opening it, you can reach the ending without seeing the egg or the paper. The easiest option is to solve the secret as soon as the box becomes available.

If the code does not work, clear the three number wheels and enter 7, 2, and 8 again from left to right. Make sure you are using the yellow box in the room with the bird outside the window. The demo also has another locked box that uses 235, so it is easy to mix up the two combinations.

Is the Secret Available on Mobile?

Yes. Rusty Lake says the secret is also inside Servant of the Lake Lite, the free mobile version. The objects and answer should be the same, but you will tap the screen instead of using a mouse. If the Lite version is not visible in your store, check that you opened the separate Lite listing rather than the paid full-game preorder page.

The secret does not unlock a paid feature or require an account. It is a small optional puzzle inside the game. Avoid any video or website that asks you to download another file, enter a login, or use a code outside the demo. The number belongs in the yellow box inside Servant of the Lake.

Does the Secret Change the Demo Ending?

The normal ending remains the same. The guests still arrive after you complete Aldous' routine. The secret adds an item and a clue for players who enjoy searching Rusty Lake games for details that may connect to a later puzzle or story.

Servant of the Lake releases on August 13, 2026, for PC, iPhone, iPad, and Android. The secret can be found now in the Steam demo and the mobile Lite version, so you do not need to buy the full game to try it.