Great article! I really like how you compare EBA and PD, and explain how thru their respective mechanics they manage to create the desired experience in the player. Also, since the concept of challenge is pretty fundamental to game design, it’s quite interesting to propose that it may not be the cornerstone of all gaming experiences.
BTW, you mention that Ouendan is EBA’s “spiritual successor”. Isn’t it the other way around (as you state later in the article)?