The goal
Every Lattice puzzle is a grid of cells joined by arithmetic. Some cells already hold numbers; others are empty. Around the board sit operators — plus, minus, times, and divide — and equals signs that tie short chains of cells into equations. You are given a small tray of number tiles. Your job is to place every tile so that all of the equations are true at once.
That last part is what makes it a logic puzzle rather than arithmetic homework. A tile that satisfies one equation also has to satisfy every other equation it touches. The right number for a cell is rarely a matter of taste — it is forced by the numbers around it.
Reading an equation
An equation is a short chain: a few cells, the operators between them, and an equals sign with a result. For example, a chain that reads cell · plus · cell · equals · 12 tells you the two cells have to add up to twelve. If one of them already shows a 5, the other must be a 7 — and if your tray holds a 7, that placement is forced.
The operators are clues, not decorations. A small product limits the factors that can make it. A large difference means one cell is big and the other small. Division is the sharpest clue of all: if a chain divides and must come out whole, the divisor has to divide the dividend, which often leaves a single candidate in your tray.
How to play, step by step
- Scan for the easiest equation. Find the chain with the fewest empty cells — ideally one. That cell has a single possible value. Solving it costs you no risk and gives you a foothold.
- Place the forced tile. Drag the tile that the equation demands into the empty cell. Every Lattice board guarantees that at least one such forced move is always available.
- Follow the cascade. The moment you fill a cell, re-read the equations that touch it. One of them may now have a single unknown it didn't before. Solve that next, then the equations it touches, and let the chain reaction spread.
- Use the operators to eliminate. Rather than asking "what could go here?", ask "what does this operator forbid?" Forbidding candidates is faster than testing them, and it is how the puzzle is meant to be read.
- Count your tray. The tiles left in your tray are a clue. If three cells remain and your tray holds exactly three numbers, those numbers go into those cells — the equations decide the order.
- Finish without guessing. If you feel like guessing, stop and re-scan. The next move is always deducible. When the last tile lands, the board is solved — and it is the only solution that exists.
The one rule: never guess
Every Lattice puzzle is machine-proven before release to have exactly one solution. That guarantee is what makes guessing unnecessary: at every point in a solve, the next number is forced by what's already on the board. If you're stuck, you haven't run out of logic — you've missed a clue. Re-scan for the most constrained equation and the path reopens.
If a board ever genuinely looked unsolvable, that would be a fault in the proof, not a feature of the puzzle — which is why the team treats "this looks wrong" reports as the highest priority. In practice, the wall is almost always a missed deduction.
Difficulty, hints, and worlds
Lattice grades each puzzle Easy, Medium, Hard, Expert, or Master — by how deep the deduction goes, not how big the board is. A small board with a long chain of reasoning can outrank a large, easy one. If you get stuck, a hint will nudge you toward the next forced move; it never hands you a guess.
Beyond the classic grid, Lattice has twelve worlds that reshape the same logic: diagonal weaves, missing tiles you mint yourself, hidden operators to deduce, two-sided balances, inequalities, rings around a hub, and even boards that wrap a 3D cube or climb a pyramid. The Guides explain each one.
Where to play
There's a free Daily Lattice every day — one proven puzzle, no account, in your browser. Or pick a world from the home gallery and work through its levels at your own pace. Once the cascade method becomes a reflex, step up a grade and see how deep you can read.