How to play the tromino puzzle
- Look at the board. Each level is a wooden board, sometimes with dark pegs that cannot be covered. The pieces in the tray cover exactly the free squares.
- Drag a piece onto the board. Touch or click a piece and drag it over the board. A green outline shows where it will snap; red means it overlaps something.
- Turn and flip. Tap a selected piece (or press Turn) to rotate it 90°, and press Flip for its mirror image. On a keyboard, R turns and F flips.
- Move or take back pieces. Drag a placed piece to a new spot, or drag it off the board to return it to the tray. Undo steps back one move.
- Fill every square. The level is solved when every free square is covered. Stuck? Hint places one correct piece for you.
The two trominoes
With turns and flips allowed, these two shapes are every way to join three squares edge to edge. Counted without flips (one-sided) the bent piece still has the same silhouette after a mirror, so the free count stays two — the number our level generator works with. Fixed orientations total 6.
Tromino puzzle strategy
- Fill corners first. A bent V fits an L-shaped corner; a straight I wants a long edge.
- Watch for pockets of 1 or 2 squares — they can never be filled by a tromino, so undo early.
- Any closed-off region must have a multiple of 3 squares or it is already a dead end.
- On boards with pegs, treat each peg as a hard wall and pack the pockets around it separately.
- Stuck? Hint places one piece that still leads to a full solution from the empty tray pieces.
All levels at a glance
Every level was generated from a random wooden board, then checked with the same Dancing Links search used for our tetromino and hexomino puzzles. Fewer solutions usually means a harder level; a “+” means counting stopped at a cap.
| Level | Board | Pegs | Pieces | Solutions |
|---|---|---|---|---|
| 1 | 3 × 2 | 0 | V V | 1 |
| 2 | 3 × 3 | 0 | I V V | 4 |
| 3 | 4 × 3 | 0 | I I V V | 9 |
| 4 | 6 × 2 | 0 | I I V V | 4 |
| 5 | 5 × 3 | 0 | I V V V V | 7 |
| 6 | 6 × 3 | 0 | I I V V V V | 26 |
| 7 | 4 × 4 | 1 | I I V V V | 2 |
| 8 | 5 × 4 | 2 | I I I I V V | 1 |
| 9 | 6 × 4 | 0 | I V V V V V V V | 12+ |
| 10 | 7 × 3 | 0 | I I I V V V V | 70 |
| 11 | 5 × 5 | 1 | I I I I V V V V | 62+ |
| 12 | 6 × 5 | 0 | I I I V V V V V V V | 12+ |
| 13 | 8 × 3 | 0 | I I I I I I V V | 40+ |
| 14 | 7 × 4 | 1 | I I I I I I V V V | 36+ |
| 15 | 6 × 6 | 0 | I I I I V V V V V V V V | 1+ |
| 16 | 8 × 4 | 2 | I I I I V V V V V V | 21+ |
| 17 | 7 × 5 | 2 | I I I I I V V V V V V | 17+ |
| 18 | 8 × 5 | 1 | I I I I I V V V V V V V V | 1+ |
| 19 | 6 × 6 | 3 | I I I I V V V V V V V | 1+ |
| 20 | 8 × 5 | 4 | I I I I V V V V V V V V | 2+ |
More shape puzzles
Ready for four squares per piece? Try the tetromino puzzle. For six, see the hexomino puzzle. For the full packing family, open the free 8×8 packing puzzle or the polyomino hub.