I really love Zachtronics card games and this collection has two good ones. The appeal of some of the other puzzle games will probably be limited as much by their vague, minimal instructions and lack of tutorials as their inherent difficulty. They just throw you in and you sink or you swim. My fav: 20th Century Food Court, an engineering sim factory builder that gave me about 70 hours of the best open ended, exploratory gameplay I've ever had in my life.