Doppelblock — Latin-square logic puzzle: blacken two cells per row and column, then fill white cells with digits 1..N-2 using Latin square rules and outside sum clues. 30 levels across 5 tiers from 5x5 Beginner to 7x7 Expert.
DOPPELBLOCK
Double Block · Latin-square logic puzzle
How to Play
•Blacken exactly 2 cells in each row and exactly 2 cells in each column.
•Fill the remaining white cells with digits 1 to N-2 — each digit appears exactly once per row and column (Latin square).
•Outside clues show the sum of digits strictly between the two black cells in that line.
•Every puzzle has a unique solution.
Why Doppelblock?
Doppelblock (German for “Double Block”) is a unique puzzle that fuses three classic mechanics:
• Shading: each row and column has exactly two black cells.
• Latin square: white cells fill with 1..N-2 each appearing once per row/col.
• Sum clues: outside numbers reveal the digit sums between black cells.
The result is a satisfying logic puzzle with three layers of constraint that reward careful deduction.
30 levels across 5 tiers from 5x5 Beginner to 7x7 Expert.
Choose Level
0 / 30 solved
Level 1
Beginner · 5×5
⏱0:00
💡3
Digit
Erase
Tap a white cell, then tap a digit below to fill it. Tap a digit twice to remove.
Solved!
★★★
Beautiful logic work!
Settings
Music
Ambient chord progression
Sound Effects
Click, hint, win
Auto-check
Highlight errors as you play
How to Play Doppelblock
Setup. The grid is N×N. Each row and column contains exactly 2 black cells — those are your constraints.
Filling white cells. The remaining white cells must hold digits 1 to N-2, with each digit appearing exactly once per row and column. (This is the Latin-square rule.)
Outside clues. A small number outside the grid means: the sum of the white digits strictly between the two black cells in that line equals that number.
Tools.
• Digit mode: tap a white cell, then tap a digit on the keypad.
• Erase mode: tap any filled cell to clear it.
• Check: validates your current state. Errors are highlighted.
• Hint: reveals one correct cell. You have 3 per level.
• Clear: removes all your entries (keeps black cells).