Fill in the grids so that every row, every column and 3x3 box contains the digits 1 through 9. There must be a one-to-one correspondence between both twins, i. e., in all positions with a certain digit in the first grid must be in the corresponding position in the second grid also always the same digit (possibly another as in the first grid).

Connect in the left grid all dots in pairs in such a way that all cells are filled. Each straight line must be at least 2 cells long. After that fill in the right grid so that every row, every column and every 3x3 box contain the digits 1 through 9. If two cells are in the left grid in the same path (snake) then the corresponding cells in the right grid must be different.

Connect in the left grid all dots in pairs in such a way that all cells are filled. Each path (worm) has to make a 90 degree turn in every cell it travels through and must contain at least one turn. After that fill in the right grid so that every row, every column, every 3x3 box and both diagonals contain the digits 1 through 9. If two cells are in the left grid in the same path (worm) then the corresponding cells in the right grid must be different.

Fill in the grid so that in the four grids every row, every column, every 3x2 contain the digits 1 through 6. The green cells have the same digit as the corresponding cells in the fourth sudoku.

Fill in the grid so that in every row and every column as well of the yellow as of the green square contains the digits 1 through 6. Additionally every marked region contains the digits 1 through 6.

Fill in the grid so that in every row and every column as well of the yellow as of the green square contains the digits 1 through 5. Additionally every marked region contains the digits 1 through 5.

Fill in the grids so that every row, every column and 3x3 box contains the digits 1 through 9. The sum of the digits within each sub-region is equal to the specified number. There must be a one-to-one correspondence between both twins, i. e., in all positions with a certain digit in the first grid must be in the corresponding position in the second grid also always the same digit (possibly another as in the first grid).

Fill in the grids so that every row, every column and 3x3 box contains the digits 1 through 9. There must be a one-to-one correspondence between both twins, i. e., in all positions with a certain digit in the first grid must be in the corresponding position in the second grid also always the same digit (possibly another as in the first grid). Numbers going along grey lines must be in increasing or decreasing order from one end to the other.

Fill in both grids so that every row, every column, and every 3x3 box contains the digits 1 through 9.