I have enjoyed doing conceptis puzzles online (and printed and in booklets) for several years now and share your web address with friends and strangers who I may see doing puzzles as they commute -- people often ask ME, too, what I am doing and where they can be obtained.
My current problem is that I have recently been diagnosed with degenerative low vision problems and now find some puzzles difficult to see contrasts. For example, I am wondering whether it is possible to have options for colours or intensity used for the crossed squares in (eg)fill-a-pix. I cannot easily see whether the square is blank or crossed but I think I COULD if the cross were darker or coloured differently from the filled in squares.(There may already be a built-in option which I have not found?)
Thank you for your help and your puzzles.