Games usually start out fairly easy and then progressively become more difficult and challenge as you get stronger and better at the game. Developers must tailor the game to flow with the learning of the game by the player.
Patterns - Enemies, strategy, non-obvious solutions, character deaths, combo's, interactive puzzle solving, tutorial, chances, strategy, experiential learning, learning through loss, skill trees,
Lenses - Easy Mechanics, power, comeback, choosing a character, loss,
In Oblivion, your level was determined by leveling up your major skills. Upon leveling up you gained points in your attributes based off how many levels you increased in that attribute category. So if you leveled up only your major skills without focusing on any of your minor skills, you could become severely under-powered in the game. The enemies you face in dungeons is dependent on your level. So if you are level 30, you will fight high level enemies wearing extremely good armor. But if your attributes are poor and you don't level up your skills properly, you could theoretically be similar to a level 15. So as you level up, the enemies you fight are similar to you, you can't just breeze through them until you are past level 60 or so, since they stop around 40.
In Dante's Inferno, the game starts off fairly easy with only two types of enemies. Each are pretty easy to defeat and are always in small numbers. However, as you progress through the levels of Hell, new and stronger enemies appear in greater numbers. This forces the player to become better as he progresses through the game. But as he progresses, he gains experience, not just in tactics, but also in skills so he becomes stronger, allowing for a more even fight.
Difficulty curve is a very common standard in the industry.
Motivations: competence, self-efficacy, achievement, self, mood management Mechanics: Goals, Feedback, Challenge, Player Journey