Binary Blocks

Binary Blocks is a board of filled and hollow squares: every row and every column holds as many of one as of the other, and nowhere three alike stand side by side. On the board lie blocks — two, three or four cells inside an outline — and every cell of a block holds the same square, though which one is not said. Few squares are given, sometimes only two; the blocks tell the rest. Here a tap walks a cell from empty to a filled square to a hollow one and back, and the board tells you only what your own squares already say: three alike side by side and a square its line has too many of take a reddish wash, and a block holding both kinds turns red all over. No hints, and nothing that checks you against the answer.

A new board every day — 8 × 8, 10 × 10, and 12 × 12 — the same for everybody, each with a single solution that reasoning alone reaches. No timer and no account needed: a board left half-done waits for you until the day turns, at midnight UTC.