Lexi-Sum

What is Lexi-Sum?

Lexi-Sum combines three ideas you may already know: Kakuro's sum-clue grid, Sudoku's guarantee that a well-formed puzzle has exactly one logical solution, and Scrabble's letter-value scoring. Here's the full ruleset, explained from scratch.

The rules

1. The grid is made of connected runs of empty cells, like a crossword. Each run reads left-to-right (Across) or top-to-bottom (Down).
2. Every letter cell shows a small number in the corner — that's the exact Scrabble point value the letter in that cell must have (same values as Scrabble tiles, shown below).
3. At the end of every run sits a dark Summary Cell — the far-right cell for an Across run, the bottom cell for a Down run — showing the total of every point value in that run. It isn't editable; it's just your target.
4. Every run, once filled, must spell a real word that fits the puzzle's category. Double letters are allowed — "LETTER" or "HIDDEN" are perfectly valid answers if the values and category fit.
5. Where an Across run and a Down run cross, they share one cell — that letter has to be correct for both words at once. This is your main deduction tool.
6. Every puzzle has exactly one valid solution. If two answers both seem to fit a single run in isolation, a crossing letter elsewhere will always rule one of them out — you never have to guess between equally-valid options.
7. Type freely — nothing is marked right or wrong as you go. When you're ready, press Check Answers to see which letters are correct, which are wrong, and your score. Keep fixing and re-checking until every cell is green.

Worked example

Say an Across run is 3 cells long in the Animals category. Using the values below: C=3, A=1, T=1 — so the cells' point clues read 3, 1, 1, and the Summary Cell at the end reads their total, 5.

CAT fits every clue and is a real animal — confirmed the moment a crossing letter from a Down word agrees with one of those three cells.

Letter values (Scrabble-style)

Common letters are worth less, rare letters are worth more — exactly like the tile bag in Scrabble. This chart is also pinned in the sidebar once you start playing, and echoed on the on-screen keyboard.