Visibility: ON
Draw on Edges: ON Panel: OFF

Draw a single closed loop that passes vertically and horizontally through all cells. The loop must go through all of the given dots. When passing through a white dot, the number of cells on one side of the dot before turning must differ by 1 from the number of cells on the other side before turning. When passing through a black dot, the number of cells on one side of the dot before turning must be twice the number of cells on the other side before turning. (Not all possible dots are given; if a line crosses two dots, ignore the other dot and count cells as if it is not there.)

See also an example image at the source link.

For automatic solution checking, the loop must be drawn in green.

Kropki Loop ("Anti-symmetry") Prasanna Seshadri

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panel

Ignore Pencil Marks (L, M, S values)

App Display
Display Theme:
Display Layout:
Timer:
Puzzle Display
Sudoku Pencil Marks:
Sudoku Normal:
Star Battle Dots:
Surface Second Color:
Tools
Custom Colors (Beta):
Floating Panel:
Quick Panel Button:
Export
Auto-Shorten Links:
Input Options
Mouse Middle Button:
Reload Protection:
Conflict Detection:
Sudoku Z/Y & XCV Keys:
Saving/Storage
Saved Settings:
Local Storage:

It's a web application and universal pencil puzzle editor capable of drawing many different kinds of pencil puzzles. You can download your puzzles as images and save puzzle links in the form of URLs to share with others.

Shortcuts Tool Instructions Youtube Tutorials List of Youtube Tutorials Steps to Create a Sudoku/Puzzle Frequently Asked Questions Discord Channel Bookmarklet to Open Puzz.Link / PZV / pzprxs / OtherPenpaFork Puzzles in Penpa+

Provide Feedback Contribute to Project Ongoing TO-DO list Changelogs Credits License

Note: This is by no means an exhaustive list. Penpa+ is not affiliated with these sources. Please contact respective owners for any further information.

Eric Fox - Dictionary of Rulesets Ryotaro Chiba - WPC Puzzles LMI - WSC IB (Sudoku Variants) Puzzle Duel Club Ropeko - Logic Puzzles List

Shading - DG (Dark Grey), GR, LG, BL (Black):
Number - Normal, L, M, S - Green, Blue, Red Sudoku - Normal, Centre - Green, Blue, Red:
Line - Green, Double:
Line - Ignore Given Line Segments:
Line - Green, Double:
Edge - Green, Double:
Edge - Ignore Edges on Grid Border / Givens:
Edge - Green, Double:
Wall - Green:
Shape - Shape - Square - Option 2:
Shape - Shape - Circle - M size - Options 1 & 2:
Shape - Shape - Corner triangle - Options 1 to 4:
Shape - Arrow - Small - Options 1 to 8:
Shape - Number - Math - Black, Green - Options 2 & 3:
Shape - Special 1 - Battleship - Black - Options 1 to 6 and Curvy Black - Options 1 to 4:
Shape - Special 1 - Tent - Option 2:
Shape - Special 1 - Star - Options 1 to 3:
Shape - Special 2 - Lightbulb - Option 3:
Shape - Special 2 - Minesweeper - Option 4:

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panel

New Grid

Board type:

Size:

White space:

*Update display* button only affects the following properties:

Display size:

Gridlines:

Gridpoints:

Outside frame:

Resize

Add/Remove Rows/Columns:

Save screenshot

White border:

Image quality:

File Type:

Rotate / Move / Add / Remove

Rotate:

Flip:

Move:

Add/Remove Rows/Columns:

Share Puzzle

Puzzle Information

Generate URL

Add/Remove Genre Tags

Extended Output

Solution will check for the following:

Custom Message

Header

Share Replay

Input/Output sudoku string

Load URL

General Settings

Welcome to Penpa+

Usage

Development

Sudoku/Puzzle Rulesets

Update display button only affects the following properties: