You don’t need me to to tell you that Portal and Portal 2 are amazing games - best-of-class in storytelling, puzzle design, and sound production. Once you’ve played both (don’t wait like I did) you may enjoy this behind-the-scenes app featuring brief stories about Valve, how Portal 1 came to be, and what challenges Portal 2 faced. It’s a great insight into the confusing, uncertain, hopelessly tentative process that produces masterpieces. In many ways it reminded me of tales of Pixar’s early days.

(Warning: the app features spoilers.)