Flowpipe

A single board each day. The entry, the exit and the whole deck of pieces are derived from the date, so on any given day everyone plays exactly the same puzzle, wherever they are.

Lead the water from the entry to the exit and fill as much pipe as you can before the time runs out. Your result is kept against your own history: a score for each day played, the streak of days in a row, and a personal best.

Every board is checked to be solvable before it is ever shown. No account, no ads.

Open source.