Normal sudoku rules apply. Clues outside the grid are "X-Snake sums". X-Snakes are basically bendy X-Sums: orthogonally connected 1-cell wide paths that begin in the cell next to the clue (the 'tail' cell). Snakes are X cells long, where X is the digit in the tail cell, and sum to the value of the clue without repeating any digits. Snakes may not touch themselves OR ANY OTHER SNAKE orthogonally. The snakes are racing to the grey rock in the centre of the pit (grid!). Exactly one cell of exactly one snake must touch the rock orthogonally or diagonally to win the race. (ie there is only ONE snake cell in box 5). Snakes don't eat rocks so neither the rock cell nor its digit may appear in any snake.