The rules
- Every puzzle here is solvable by reasoning alone. You never have to guess.
- Got it
- Cut the whole grid into rectangles, one number inside each.
- Partition the whole grid into axis-aligned rectangles. Every cell belongs to exactly one.
- Every rectangle contains exactly one number.
- That number is the rectangle's area, in cells.
- Drag from one corner of a rectangle to the opposite corner to draw it; anything it covers is replaced. Tap a rectangle to remove it, or an empty cell to draw a 1 × 1.
- Only a rectangle already drawn wrong is marked live — the wrong area, no number inside it, or two. A cell left empty is not marked until the whole board is judged — so a board with no warnings on it can still be unfinished.
How to play here
Three ways to play
Campaign
Chapters that start gently and bring in one new idea at a time.
Daily puzzle
A new board every day, the same for everyone. Solve every one in a month and that month's trophy is yours.
Endless
Keep going as long as you like, in Easy, Medium, Hard and Expert.
Common questions
Is Modulus free?
Yes. You can play here without paying and without an account. Ads keep the lights on.
Where is my progress saved?
In this browser, on this device. If you clear the site data, your progress goes with it. A free Solvarium account keeps it safe.
Does it work on a phone or tablet?
Yes. It runs in any current browser on phones, tablets and computers, and the board resizes to fit the screen.
Does every puzzle really have one solution?
Yes. Every board goes through a solver before it ships, and anything with more than one solution is thrown out.