Mosaic Logic

You fill a square grid with coloured tiles using three overlapping sets of clues — one per row, one per column, and one per irregular zone — and the finished grid turns out to be a picture.

Content outside the code

Pictures live in pictures/, one text file each. Nothing about a picture is written in Dart.

That boundary is the whole reason the game is sustainable. Puzzle games die when adding a level is an engineering task, because then levels only get added on the days you feel like programming. Here a picture is a text file, so designing one is a completely different activity from building the game — and one that can happen on a train, or be contributed by someone who doesn't write code.

The third clue set

Rows and columns alone give you a nonogram. The irregular zone is the addition, and it changes the solving experience: zones cut across the grid's symmetry, so deductions propagate diagonally and the puzzle stops being two independent one-dimensional problems interleaved.