Balancing Challenge Against Frustration In Games 156
Game-ism has an article discussing the balance game developers strive to achieve between making games challenging enough to be interesting, but not so much that they are frustrating. The author points to Assassin's Creed and GTA IV as examples of recent major titles which may have suffered from gameplay that was too easy to master. Conversely, a minor title like Bionic Commando Rearmed achieved more success than expected in part due to the sense of accomplishment that comes from completing parts of the game.