David Nicholls posted a comment on discussion Open Discussion

As suggested in other replies, you can save the puzzle in image format (say 800*800 pixels) and use a drawing program. I use Paint3D in Windows 10 because it has Select and multi-step Undo buttons. These only work with 3D objects, not 2D. There isn't a 3D line object, so I draw narrow cubes (also use a 2-pixel pen). You have to rotate the simulated line if necessary. If a chain doesn't produce any candidate eliminations, you can undo your links one by one to search alternative paths. I use a Concrete...