Themed 7x21 Chocona

Question

Chocona rules differ from Chocolate Banana rules.

There is a hidden message inside the solution of the puzzle. An answer will only be accepted if it correctly identifies said message. The message is not SNY.

The 30 cell is given as non-shaded.

P.S. I promise this is my last grid puzzle of the week. I'm getting carried away :) I'll find something else.

Normal Chocona Rules apply.

Rules:

1. Shade some of the cells.

2. Shaded cells linked orthogonally must always form a rectangle (or a square).

3. Non-shaded cells linked orthogonally may form rectangles (or squares).

4. A number indicates the number of shaded cells in its region.

5. The solution is unique. You do not need this information to solve the puzzle.

Click on the image to use the online solver and view the rules.

Answer 1

The hidden message is:

HELLO!

As seen written in the solution:

---

Step by step:

1.

To start, can fill in all regions where the number matches the number of available cells:

Looking at the 5 in the middle right, surrounding the 2. The 3 cells on the left must all be unshaded as they cannot form a rectangle with the 1s. So 5 of the 6 remaining cells are shaded. There a couple of possibilities, but it is either of the 2 bottom cells that are unshaded, so the rest must be shaded.

Now consider the 30. There are 34 remaining cells, of which 30 need to be shaded, so it'll be easier to work out what cells can't be shaded instead.
The bottom left cell must be unshaded as it cannot form a rectangle. If the cell above the 5 was shaded, the cells either side would have to be unshaded, but then there wouldn't be enough cells to cover the 2, so it must be unshaded. This in turn means one of the cells to the left of this must be unshaded to deal with the column of 1s and the 5. The remaining unshaded cell must be bottom right to deal with the three 1s, so we can shade a lot of cells in with this knowledge, including finishing off the 5 mentioned in step 2:

The unshaded cell bottom right can't be the lower cell, so the bottom is connected. Going through the grid now and marking cells that can't be shaded green helps see a few final steps:

The 1 in the 'S' that is not yet solved must have it's shaded cell on the right. The entire left side can now be solved from the column of shaded cells on the left side of the 30 region forcing the touching 1s to have their shaded cells on the left. The bottom of the 3 in the middle cannot be shaded, so the rest are all shaded. The 5 then must loop round the 3 and touch the 1s, and we can solve the top row to finish the grid:

Finally, we can see in the middle of the grid, the word 'HELLO' written in the unshaded cells, as the secret message!