Ttphtpthpthtpth
by myShoggoth
Play at:

Normal sudoku rules apply. Digits along a gray palindrome line must read the same from both directions. Clues outside the grid indicate the sum of the first X digits in that row or column, where X is the first digit seen. Cells separated by an X must add up to 10, those separated by a V must add up to 5. Not all Xs and Vs are necessarily given.