A site with 1 billion mazes 'One Billion Mazes'

When you display the maze, the PDF file opens so that it sticks to the bottom of the page, so you can not see the entire page, so you can play by scrolling while watching your current location. You can play it with a good feeling.

Exactly One Billion Mazes to Solve

Some mazes are so complicated that answers are attached in the second half. It seems interesting to display the PDF file on a mobile terminal.