Doubletake, a daily spot-the-difference game and the machine behind it

What it is

Doubletake is a browser game at doubletake.day. Every day one image pair opens with six differences in it. The game starts with no account and no ads, the result stays in the browser, and the next picture arrives at midnight. The idea is the same as Wordle's: one round a day, no more.

We built it as our own product to test one thing in practice: how far daily-refreshing content can be automated without leaving quality to guesswork.

How one day is made

• Illustration. The base picture is generated in the same ink-and-wash style every day. The style was chosen once and it stays, so the game looks like itself and not like a stock library.
• Composing the differences. The differences are not filters laid over the image. Every object is cut out separately and placed according to a plan file: one added, one removed, one recoloured.
• The quality gate. Before release a machine checks the pair: are the differences big enough to be found on a phone screen, are they far enough apart, and is there a single differing pixel outside the marked circles. The measurement is taken from the compressed image actually served to the player, not from the master.
• The daily queue. An approved pair goes into the queue for its own date. Tomorrow's picture cannot be fetched early.

One day's puzzle takes about fifteen minutes through this chain. A week of content is roughly two hours of work.

Why a company might care

The game is ours, but the machine is not tied to it. The same chain turns into a company's own look: your imagery, your products in the pictures, your domain. It gives a visitor a reason to come back daily, and keeping it running does not require anyone at a desk every morning.

The first shape we sell it in is an advent calendar: 24 doors, an image pair behind each one, the client's own products hidden in the pictures. There is one at pohjastudio.fi/joulukalenteri. The same chain also bends into a shorter campaign or a continuous daily game.