Logic Masters Deutschland e.V.

I deleted this yesterday as I thought it was too hard to understand the rules, but then I thought, oh well, someone may want to solve it, someone may not, so no harm leaving it up.

No graph theory required to solve this, but for anyone interested, the journey you are trying to find will be considered a semi-hamiltonian trail. The rules are somewhat long, but all line constraints are fairly standard. The rest is all just making sure I've covered every base of what people might wonder as they solve the puzzle. I've tried to keep stations in their relative positions in real life, with lines that actually service each station, but of course, some lines take a bit of a wobbly journey! Thanks and hope you enjoy!

Puzzle: London Underground Commute

Rules:

Normal 9x9 Sudoku Rules apply.

Starting at King's Cross, you must visit every station before arriving at Waterloo. Station's may be visited more than once, but a line connecting two stations can only be used once. Any line taken between, and including, the two stations it connects must obey that lines constraints. The rest of the line may or may not obey that line's constraint. A new line segment begins leaving every station, regardless of whether it is the same type of line going in and out.

Line Constraints (These apply only to the lines used on your journey between, and including, the stations where it is used):

Northern Line (Black): Digits along a black line are region sum lines. Digits must sum to the same value for each box it enters.

Central Line (Red): Adjacent digits along a red line must differ by at least 5.

Victoria Line (Light blue): Digits on a light blue line form a palindrome. They must read the same in either direction.

Piccadilly Line (Dark blue): Dark blue lines are modular lines. Every 3 cells along the line must include a digit from 147, 258 and 369.

Bakerloo Line (Brown): Digits on a brown line are entropic. Every 3 cells along the line must include a digit from 123, 456, 789.

Jubilee Line (Light Grey): A light grey line is also an entropic line but with the added constraint that both connected stations are column indexers. That is, the digit in a station in column X, indicates where the digit X goes in the row.

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