Fill the grid using the number clues. Every finished picture is a little creature that moves into your Codex.
Pick a grid. New creatures first, then repeats.
The grid is hiding. Clock's stopped.
Numbers beside each row and above each column are the runs of filled squares in that line, in order. 3 1 means a run of 3, at least one gap, then a run of 1.
Tap or drag to fill. Switch to ✕ Mark (or right-click) to mark squares you know are empty. A clue dims when its line is right.
Finish the picture and meet the creature hiding in it.