Because his puzzle-games collection are computer games you can play yourself, they can be found here: https://www.chiark.greenend.org.uk/~sgtatham/puzzles/
Or in the appstore/playstore.
My current timewaster is 'patterns',a nonogram puzzle
My current timewaster is 'patterns',a nonogram puzzle
I assume that the interest in games and the hostname of his webserver are very much related.