In a recent interview with Eurogamer, Nintendo's Shigeru Miyamoto spoke at length about the creation of Super Mario Bros.' World 1-1, one of the most iconic levels in video game history. 

Designed to be a tutorial level, Miyamoto explained that World 1-1 contained everything needed to help the player “gradually and naturally understand what they’re doing.” He wanted players to quickly “learn what the game is all about” so that they can “start to play more freely." 

According to the Mario creator, that’s the approach Nintendo tries to take with all of its games, because “once the player realizes they need to do, it becomes their game.”