Logic Masters Deutschland e.V.

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Normal sudoku rules apply.

Quadruples, Xs and Vs are standard, but a negative constraint applies so you should read all rules.

You are the conductor of the Cosmic Express, an intergalactic locomotive. Your job is to pick up three aliens and drop them off in their homes. The two purple aliens (R4C5 and R6C5) must each be dropped off in one of the two purple homes (R1C1 and R1C9), while the orange alien (R5C5) must be dropped off in the orange home (R9C5). The Cosmic Express enters the sudoku grid in the bottom left cell (R9C1; the start of your path) and exits it in the middle right cell (R5C9; the end of your path), moving through the grid orthogonally. Only the entrance and exit cells are given, you determine how the train turns from and to those cells. You cannot visit any cell more than once, nor can you cross your own path. Also, you cannot move through an alien or an alien home.

The Cosmic Express automatically picks up an alien when its path orthogonally touches that alien's cell - however, an alien will not be picked up if the Cosmic Express is at its carrying capacity (two aliens). The Cosmic Express automatically drops off an alien that is currently aboard it when its path orthogonally touches a cell corresponding to a home (assuming that home's color matches the alien, as previously described) - however, an alien will not be dropped off into a home that already had a different alien delivered to it.

Region Sum Line: The path that the alien train takes is an atypical region sum line. Every visit to a box counts towards the same total for that region. In other words, the sum of all path digits in box 1 equals the sum of all path digits in box 2, equals the sum of all path digits in box 3, …

Alien Product: The product of the digits on the aliens is equal to the sum of the region sum line.

XV: Cells separated by an X sum to 10. Cells separated by a V sum to 5. EVERY possible X and V where both separated cells are not along the path is given (and every X and V separate cells not along the path).

Even homes: Every alien home has a cell with an even digit.

Quadruple circles: Each digit shown on a quadruple clue appears at least once in its four surrounding cells. A digit listed twice must appear at least twice in the surrounding four cells.

SudokuPad Puzzle Link