Super Sumoku

The board is a grid of numbers (7×7 by default — also 8×8, 7×6 or 6×6, chosen with the selector top-right). Each row's target sum is shown on the right and each column's along the bottom. On the square boards the main diagonal's sum sits in the bottom-right corner (◢) and the anti-diagonal's on top of the row-sum column, top-right (◣); the rectangular 7×6 board has no diagonals. The sums only count the cells you keep included.

Click a cell to cycle its state:

• 5 Included — counts as +5 (the starting state).
• 5 Excluded — a big ✕ is drawn over it; it counts as 0.

Long-press any cell (or press M / hold Space/Enter on the keyboard) to mark it with a blue highlight — a visual reminder independent of its state. You can mark included, excluded, double, and negative cells alike.

Work out which cells to exclude so every row, column and both diagonals hit their targets. A matched line turns green with a short beep. Match all sums to win!

Options

Turn these on with the checkboxes — each option has its own puzzles for every difficulty:

• 5×2 Double adds a state that counts twice the number (here +10); the ×2 shows to the right of the number. Toggle becomes: included → excluded → double.
• −5 Negative adds a state that counts the negative of the number (here −5); a red − (or +) shows in front of the number. Toggle: included → excluded → negative.
• Turn on both for a 4-way toggle: included → excluded → double → negative.

Grid sizes

Pick a board with the size selector top-right (next to Instructions). Every size has its own puzzles for each mode and difficulty:

• 7×7 — the default, a balanced board with a true centre cell. A good place to start.
• 8×8 — the larger, expert board: more cells, longer chains and the toughest X-Hard puzzles. Recommended once 7×7 feels easy.
• 7×6 — a quicker rectangular board (7 rows × 6 columns). Great for a short game on a phone. It has no diagonals (a rectangle has no meaningful diagonal), so you only match the row and column sums.

Each puzzle shows a measured Difficulty (1–100). Press 💡 Hint to highlight a line or area to focus on — no answer revealed. Press again for a nudge with the current sum vs the target. Press a third time (or more) for the exact cell to change. ✓ Check marks any of your excluded / double / negative cells that are wrong with a red dot — tap the board to clear it. Tap any sum to highlight its whole row, column or diagonal and see that line's current total (plus the contribution of your marked cells). Long-press a sum to mark that whole line at once (long-press again to unmark it). Reset reopens every cell and New Game draws another puzzle (both ask first). Keyboard: arrow keys move a cursor, Space/Enter cycles the cell, M marks/unmarks, U undo, H hint, C check, Esc clears highlights. The 🔊 button mutes or unmutes all sounds.