Jonathan NifeneckerAs a programmer and logic game lover, I programmed a few softwares to scan all the possible challenges of differents games.
With such database, I then printed 100's of very challenging game that will now be available to you.
You will love those games if you can get through all the provided level and need more.
Disclaimer : Those will probably be too hard for the average persons. Those are niche items for peoples passionate about puzzles :)