Logic Masters Deutschland e.V.

A new selection of puzzles initially made for Discord only. I hadn't planned on publishing any other packs here after the Discord Line Squadron one, but the belows compelled me to. For one, they're simply the 6x6's that I'm the proudest of, and also they serve as the second tier of trilogies leading to puzzles from my main Doppelganger offering here on LMD, that are generally maybe not the best choices for a coffee-break solve; so this pack is designed to give as close an experience to these 9x9's as I could manage to provide in a 6x6 format, to the solvers who have no intention of ever trying the larger ones but would still somehow like a taste (The first Tier, made of 4x4's, is offered further below as a warmup, or for sampling)


The puzzles are presented here in alphabetical order, though as it is, the order of difficulty is probably the exact opposite, and the difficulty of each puzzle is not necessarily representative of the overall difficulty of its trilogy (Buttered Cat Paradox and Solaris are the hardests in these trilogies). Also, not represented here is the Standard Arrow Trilogy, leading to the Greater Doppelganger, as for this one, you can play the Lesser Doppelganger here, and here is a quick link to the last tiers of the trilogies

RULES

DOPPELGANGER
– Every row, column, and box contains the digit 0 always, as well as five out of the six digits from 1 to 6 (ie, it's missing one digit that is not 0)
– No two row, no two column, and no two box may be missing the same digit
– For each 0 in the grid, the digits missing in its row, its column, and its box must be three different digits, yet zero always has a null value


COORDINATE ARROWS
– Digits on an arrow spell out the coordinates for the digit that is their sum
– The row number is written on the start of the arrow, the column number is written on the arrow tip (eg, if an arrow looks like this: -1 4-> there must be a 5 in r1c4). All the arrows must correspond to different coordinates, though digits may repeat on an arrow if allowed by the other rules
SKYSCRAPERS (row 0 and column 0)
– The digits in the grid act as skyscrapers of heights corresponding to their values. Numbers outside the grid show how many digits that can be seen in the corresponding row/column. Taller buildings hide shorter buildings (none of the actual numbers, if any, are given; they would need to be deduced by the solver)
– For the purpose of skyscraper counting, the digit 0 is null, and does not count as a skyscraper


SPIRAL GALAXY
– The dots in the grid are the centers of non-overlapping, 180 degrees rotational symmetric galaxies. Each cell of the grid is part of a galaxy (1x1 galaxies can be valid, but they must have a center)  
– The galaxies in this puzzle are made of a series of non-repeating consecutive digits in any order


DUTCH WHISPERS
– Adjacent digits along an orange line must differ by at least 4


XV
– Pairs of cells connected by a V must sum to 5 in total value
– Pairs of cells connected by an X must sum to 10 in total value
DOUBLERS
– Six cells in the grid are doublers, which means that a digit in such a cell counts as double in value
– There is exactly one doubler in each row, column, and box, and they form a set of the digits 1 to 6 (so a doubler cell cannot contain a 0)