There are 17 shapes: dot, dominoes, lines of three to five, two squares, four corners, an L, a T. Each tray piece is chosen at random from them.
Block Puzzle has 17 different shapes. None can be rotated (see why).
- Dot: one square.
- Dominoes: two squares, horizontal or vertical.
- Lines of three, four and five: each horizontal or vertical.
- Squares: 2×2 and 3×3.
- Corners: a three-square L in each of four orientations.
- Large L: five squares, three down and three across.
- T: four squares, three across and one below the middle.
How the tray is filled
Each of the three pieces is picked at random from all 17, with an equal chance. The tray refills only after all three are placed. There is no guarantee that a given piece will fit, which is why the game can end with squares still empty.
Keeping space for the big shapes is covered in the strategy guide.