How we make puzzles
Splash Logic is an independent studio making calm, fair puzzle games. Kakuro is our first game. This page explains how a puzzle gets made, because that is the part we care most about.
By Splash Logic · Updated 20 September 2026
Most puzzle apps generate a board on your phone, the moment you ask for one. That is fast, and it is why players of other apps run into puzzles with two answers, puzzles with none, and puzzles that can only be finished by guessing. We do it the other way round: the work happens on a computer here, long before the puzzle reaches you.
The four steps
1. Generate
A program builds a candidate board: the shape, the black clue squares and the totals.
2. Prove there is exactly one answer
Two separate solvers, sharing no code, each solve the board. If they disagree, or if either finds a second answer, we throw the puzzle away. One of them is a general constraint solver, used precisely because we did not write it for this job.
3. Prove it can be solved by reasoning
A third program solves the board using only named human techniques, and never guesses. If it cannot finish, we throw the puzzle away. Its list of steps also becomes the hint chain, which is why a hint in the app can tell you why a square must hold a particular digit.
4. Rate and playtest
We rate each surviving puzzle by the techniques it needs and where its hardest moment falls, then order them so difficulty rises in a way that feels fair. Then people play them.
What that means when you play
You will never meet a puzzle that cannot be solved by reasoning. If you are stuck, the answer is always somewhere on the board, not behind a guess. That is the whole point of the game, and it is worth the extra work.
The studio
Splash Logic was founded in 2026 and is based in Germany. We are small, we read what players write to us, and we would rather ship one careful game than five quick ones.
Questions, bugs or a puzzle that looks wrong: [email protected].