Behind the scenes: how we build 3,330 puzzles
3,330 puzzles is a lot. Designing five a day by hand would take almost two years. So we took another route: a program that builds puzzles from rules we define, and a second program that checks every single one before players see it. Here is how it works.
The same puzzles every time, yet none alike
The generator uses a random number generator with a fixed seed, so every run produces exactly the same 3,330 puzzles. The benefit: the game on your device and our server always agree on what each puzzle is, without shipping huge amounts of data back and forth.
The difficulty curve
Every puzzle has a difficulty score that rises with every puzzle, from 1.0 on the first to 10.0 on the last. That score drives several things at once:
| What changes | Early puzzles | Late puzzles |
|---|---|---|
| Code length | 3 letters | 8 letters |
| Steps per puzzle | 1 | 4 |
| Keypad | 3×3 | 5×5, shuffled |
| Precision needed | ±10 pixels | ±3 pixels |
| Decoy strokes | 0–2 | 10 |
New mechanisms unlock gradually in the first rooms, and the puzzle where a mechanism first appears always shows an explanation card.
The no-repeat rules
“No repeats” means more than unique codes. We layered several rules so that every puzzle feels new:
- All 3,330 codes are unique, and none repeats a letter three times in a row.
- Neighbouring puzzles always use different main mechanisms.
- Every room uses at least four main mechanisms.
- The same combination of mechanisms does not return within 30 puzzles (fewer early on, when there are only a few mechanisms to choose from).
- Symbol sequences never simply walk the buttons in order, like 1-2-3-4.
The solver
Every generated puzzle is checked by a second program we call the solver. If a puzzle fails, the generator throws it away and builds another. Among other things, the solver checks that:
- it is solvable and has exactly one answer;
- no single layer reveals the code — in layered mechanisms every letter is spread over at least two layers, and no layer holds almost all of a letter;
- sliding puzzles need the right number of moves — the program computes the true minimum and rejects boards that are too easy for their floor;
- hidden objects are tappable — eyes are far enough apart for a finger on a phone;
- average difficulty rises on every floor.
All of this takes less than a second for 3,330 puzzles.
What software cannot tell us
A program can tell us a puzzle is solvable, but not whether it is fun, or too hard for real people. That is why we collect anonymous statistics such as each puzzle’s average time and magnifier use, to find odd puzzles and improve them over time.
If a puzzle ever feels wrong, tell us. Feedback from real players is the most valuable thing we have.