While it may be better suited to mobile these days, World of Goo is a great puzzle/bridge-building game with a simple mechanic it explores well.

A fresh, visceral and addictive hyperactive trip of ultraviolence, strategy and style. Finds its rhythm immediately and sticks the landing. Hell of a soundtrack too.

Kinda unlike anything else. Despite a few technical issues, Cart Life is a really rewarding game about connections and emotions. Great art and music. Challenging in more ways than one.