This is an Easy as LITS puzzle (LITS variation), where you shade cells to form tetrominoes

Rules taken from Grandmaster Puzzles:

  • Shade exactly four connected cells in each outlined region, to form an L, I, T, or S tetromino.
  • All shaded cells are connected with each other.
  • No 2×2 group of cells can be entirely shaded black.
  • When two tetrominoes in adjacent regions share an edge, they must not be of the same type (L, I, T, or S), regardless of rotations or reflections.
  • The letters outside the grid indicate the first tetromino encountered in the corresponding direction.

An example puzzle and its solution, taken from Grandmaster Puzzles (who in turn credit Chris Green):


Now, solve this puzzle:

the real puzzle

Note: if you want to solve this on the image, clickthrough to get the full size version

First answer with a fully-explained logical solution path gets the checkmark.


First, a few regions can be assigned shapes:

S must go in all three of the top regions.
enter image description here
And then L must go in the right region.
enter image description here

Now, the break-in:

Where is the L seen by column 3?
It can be either in the center region, the left region, or the bottom left. If in the bottom left, we can't satisfy the S; if in the left, then we can't connect to the top left S. So it must be in the center.

enter image description here

And now we can resolve most of the grid:

Note that the S in the top right can't connect left. This means it must go down and around. And in each of the regions, there's only one way we can place a piece to extend the shaded cells.
enter image description here

And with some connectivity arguments, the puzzle is solved:

The left region cannot connect the bottom to the top; it would have to use an L, and then there's no way we could attach the L in the middle region.
So the top-left region must go down and to the right, which places the L; finally, a T in the left region finishes off the puzzle.
enter image description here


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