As part of his keynote to open DICE 2012 titled "Why we create, why we play," Bethesda Studios creative director Todd Howard dropped a shocking figure. Data from Steam shows that gamers playing Skyrim on PC have racked up an amazing 75 hours of average playtime. This figure served as the exclamation point, driving home his point that the key to avoid people putting down a game is to hit the challenge "sweet spot." Too difficult, and it ends in frustration; too easy, and there's no sense of pride to be earned. Getting it right, though, is a tough challenge that comes from interweaving the different stages of play.

Howard described four basic stages of play as learning, playing, being challenged, and surprise. Early on in a game, a player progresses through these in a rather linear fashion. They learn the way the game works to then move into playing it. Once they have that down, the content challenges them to use what they've learned and practiced. And then finally the designer works in moments of surprise to keep the player from falling into a rut.

One of the ways Howard's team applies this idea to hitting the challenge sweet spot is by weaving the stages together as the game progresses, nesting the stages together so that it becomes a more complex combination. PC allows the game to go a step further with the addition of mods through the Creation Kit. The changes they can bring to the game add a tremendous amount of variety. They naturally lend themselves to adding surprise elements, but their reach goes into the other three elements as well. New ideas introduced in a mod may need to be learned, or at the very least played, and once they are new options for challenge open up.