Level 253 solution

Solver-verified route

1. Place Piece 1 across column 6 row 3, column 6 row 4, column 6 row 5, column 6 row 6.
2. Place Piece 2 across column 1 row 4, column 1 row 5, column 1 row 6, column 1 row 7.
3. Place Piece 3 across column 4 row 7, column 5 row 7, column 6 row 7, column 6 row 8.
4. Place Piece 4 across column 7 row 6, column 7 row 7.
5. Place Piece 5 across column 1 row 3, column 2 row 3, column 2 row 4.
6. Place Piece 6 at column 2, row 5.
7. Place Piece 7 across column 3 row 3, column 4 row 3, column 3 row 4, column 4 row 4.

Part of the "Master columns" chapter. The solver certified 1000+ solving lines with 91% of in-between placements being dead ends, for a difficulty score of 20.0 (grade 5 of 5).