A new picture arrives every day at midnight UTC, cut into the same 36 pieces for everyone. The picture guide shows it whole before you start; studying it costs nothing, because the clock starts with your first move.
Drag a piece onto the board, or tap it and then tap its slot. A piece only goes into its own slot, on the edge or beside a piece already placed, so start with the frame. Put pieces down anywhere to sort them; Shuffle re-deals the tray, and Edges narrows it to the ring you are building. Your pieces and time are kept, so you can leave and come back.
Yesterday's puzzle, and every one before it, stays in the archive, with a numbered key to its solution.