Logic Masters Deutschland e.V.

Previous Dutch Flat Mate Puzzles
This has been a weekly series since '18 Oct 23'. Here is a spreadsheet link for all the previous puzzles in the series, which also has a few teasers for upcoming constraints/guest setters in the series (subject to change). This alternative link offers a limited LMD search for Dutch Flat Mates.

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As the bold title above says, this is Episode 150 of the series. Hence the fancy flag aesthetics on the puzzle, and hopefully you will appreciate the effort to subtly include "150" in the clues on the left of the grid. It's incredible that this, originally admittedly a silly little idea, is still going; and without doubt the episode quality has improved since the early days, which was the whole point of the series.

Spoiler warning: I briefly considered ending the series at Episode 150, but realised that Episode 159 would be a far more apt end point for Dutch Flat Mates. After that the weekly side of things will certainly end, and I will take a well deserved break. More on that in the future, but it has been a pleasure reaching this milestone. Thank you to all the guest setters, and thank you so much to all the solvers. x

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Special Thanks
Thank you to palpot for sharing the setting of this puzzle with me. It went back and forth whether it was collab or not, as I had a finished solo draft (with minor issues). It's probably fairer to say this was a 'consultancy role' with one or two ideas from palpot, rather than a true collab - haha.

My introduction to this constraint was from Crusader175. Whilst Crusader175 came up with the constraint idea independently, he has since told me that he has found an old RockyRoer puzzle with the same constraint. Puzzle links are listed below, with both puzzles well worth checking out:

• Yggdrasil by Crusader175
• Circled X-Sums by RockyRoer

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To play the puzzle, please click the image:

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Puzzle Link: Click Here

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Alternate Link: Click Here (Simplified Aesthetics)

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Initial Setter Difficulty: 3 / 5

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Normal Sudoku rules apply
Place the digits 1-9 so that they do not repeat in any row, column, or 3x3 box.

Dutch Flats
Every 5 in the grid must have a '1' directly above it or a '9' directly below it. It may have both, but it doesn't need both.

Circled X-Sums
Circle one cell in each row, column, and box. Digits may not repeat on circled cells. Clues outside the grid indicate the sum of the first X digits in the corresponding direction, where X is the digit placed in the circled cell in that row or column.

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Hint to start

The overlap in Row 4 is a quick win. Remember that X is the same for both clues in that row.
Limiting options for X for each clue, whilst keeping 5s happy will serve you well.

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Guest Setter Debut
Next week we have one of the true A-Tier variant Sudoku setters making his series debut! ThePedallingPianist —who has a weekly LMD series of his own that is well worth checking out if you haven't already: 'Fortress Fillomino Friday's' (Episode 1 linked below)— has now officially joined Team Flat Mate! This is at least the second puzzle he has created using the Flat Mates constraint, but the less said about his 'CTC-featured' first puzzle (also, begrudgingly, linked below), the better! - haha

• Fortress Fillomino - Index Lines (6x6) by ThePedallingPianist
• Moving Day? by ThePedallingPianist