Sudoku Adventure 2025
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1
Advent 2025: Day 1
Rules
- Normal 6x6 sudoku rules apply
- Digits adjacent on the line must differ by no more than 1
2
Advent 2025: Day 2
Rules
- Normal 6x6 sudoku rules apply
- Digits adjacent on a line must differ by at least 2
- Digits separated by a black dot have an exact ratio of 1:2; ALL such dots are given
3
Advent 2025: Day 3
Rules
- Normal 6x6 sudoku rules apply
- Every set of digits on a line must contain one digit from each group of 1&4, 2&5, and 3&6
- Digits separated by a white dot are consecutive while digits separated by a black dot have an exact ratio of 1:2; not all dots are necessarily given
4
Advent 2025: Day 4
Rules
- Normal 6x6 sudoku rules apply
- Digits in a circle must appear somewhere within the four cells directly surrounding that circle
- Cells with a square contain an even digit
5
Advent 2025: Day 5
Rules
- Normal 6x6 sudoku rules apply
- Digits in diamonds attached by a line must differ by at least 2 and any other digit on the line must lie OUTSIDE the range of those two digits
- Digits separated by a V sum to 5; ALL such V symbols are given
6
Advent 2025: Day 6
Rules
- Normal 6x6 sudoku rules apply
- Lines are divided into segments by the borders of 3x2 boxes; digits on a segment have the same sum as any other segment on the same line
7
Advent 2025: Day 7
Rules
- Normal 6x6 sudoku rules apply
- Digits on a line sum to 7
- The digits which appear either side of the marked 7 ALWAYS appear orthogonally adjacent to one another in some way throughout the grid; any other pair which sums to 7 must NEVER be orthogonally adjacent
8
Advent 2025: Day 8
Rules
- Normal 6x6 sudoku rules apply
- The four cells surrounding the circled 8 sum to 8
- Digits on a line/shape are a consecutive group (although not necessarily in order) without repeats
9
Advent 2025: Day 9
Rules
- Normal 6x6 sudoku rules apply
- Clues outside the grid function as both 'sandwich sums' and 'X-sums' i.e. they give the sum of digits between the 1 and 6 and the sum of the first X digits counting from the direction of the clue in that particular row/column, X being the digit directly adjacent to the clue
- The 9 cells with circles contain exactly three sets of the same three digits
10
Advent 2025: Day 10
Rules
- Normal 6x6 sudoku rules apply, but with a set of six digits in the range 0-9 (not necessarily 1-6!) to be determined by the solver
- Digits on the line do NOT repeat and are NOT consecutive with ANY other digit on the line
- Digits separated by a white dot are consecutive while digits separated by a black dot have an exact ratio of 1:2
11
Advent 2025: Day 11
Rules
- Normal irregular 6x6 sudoku rules apply
- Digits on a line form a palindrome i.e. read the same in either direction
- Digits in the four cells which surround a diamond must sum to 11
12
Advent 2025: Day 12
Rules
- Normal 6x6 sudoku rules apply
- Digits on a straight line must form a valid 12-hour time (hh:mm or h:mm) when read from left to right or top to bottom
- Digits on a single line must also sum or multiply to 12
13
Advent 2025: Day 13
Rules
- Normal 6x6 sudoku rules apply
- 1 and 3 are ‘unlucky’ digits in that they cannot be orthogonally adjacent to any digit they are consecutive with.
- Digits on the triangle must be one from each pair of 1&4, 2&5, and 3&6
14
Advent 2025: Day 14
Rules
- Normal 6x6 sudoku rules apply
- Digits in cages must sum to 14 and each cage contains a UNIQUE set of digits; digits in cages may not repeat
- Digits separated by a white dot have difference of 1
15
Advent 2025: Day 15
Rules
- Normal 6x6 sudoku rules apply
- Digits placed in column 1 indicate the column within the same row where the digit 1 is placed; the same applies for digits in column 5 with regard to the digit 5
- Digits in cells separated by a V must sum to 5
16
Advent 2025: Day 16
Rules
- Normal 6x6 sudoku rules apply
- Digits on a line either remain the same or increase as they move away from the circular end of the line
17
Advent 2025: Day 17
Rules
- Fill the grid with the digits 1-7 so that no row, column, or marked 3x2 box contains a repeated digit
- Each pair of digits on a line the same distance from their connected circle must sum to the digit within that circle
18
Advent 2025: Day 18
Rules
- Fill the grid with the digits 1-8 so that every row, column, and marked 3x2 box does not contain a repeated digit
- Digits in circles appear ONLY within circles and appear exactly as many times as their value
- Digits separated by a white dot have a difference of 1 while whose separated by a black dot have an exact ratio of 1:2; all dots are not necessarily given
19
Advent 2025: Day 19
Rules
- Fill the grid with the digits 1-9 so that every row, column, marked 3x3 box, and EVERY diagonal does not contain a repeated digit
- Digits on arrows sum to the digit within their connected circle
20
Advent 2025: Day 20
Rules
- Normal 6x6 sudoku rules apply but with the digits 0-5 instead of 1-6
- Clues outside the grid function as both 'sandwich sums' and 'little killers' i.e. they give the sum of digits between the 0 and 5 in that row/column and the sum of all digits along the diagonal their arrow is pointing at
21
Advent 2025: Day 21
Rules
- Normal 6x6 sudoku rules apply
- Digits on a line do not repeat and alternate between even and odd values as they move along the line
- The sum of digits on each line is unique
22
Advent 2025: Day 22
Rules
- Normal 6x6 sudoku rules apply
- Digits adjacent on a line must differ by at least 2 and each line forms a palindrome i.e. it reads as the same sequence of numbers from either end of the line
23
Advent 2025: Day 23
Rules
- Normal 6x6 sudoku rules apply
- Digits in circles are odd and describe how many odd digits lie on the line which passes through them (repeated digits, if any, count towards that total); the same applies for squares and even digits
- Digits separated by a black dot have an exact ratio of 1:2
24
Advent 2025: Day 24
Rules
- Normal 6x6 sudoku rules apply
- Any line with a 2 on it must have adjacent digits on the line differ by at least 2, while any line with a 4 must contain a consecutive set of digits without repeats
- Lines completely without 2 and 4 are permitted as long as they do not act as though they do contain one/both of those digits
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