There is an interesting essay on The Game Design Forum about “Acceleration Flow” or the rate of leveling up in video games. The author spends a couple thousand words examining the psychology around leveling up a character or hunting down loot in a game. His points mimic others that I’ve read on keeping gamers at the controls by offering rewards at the perfect pace. Too many rewards too quick and the player is over powered and quickly bored.
Brokenness, especially the experience correction, can be a letdown after the thrill of acceleration. Following any acceleration will be the period of god-like ease. Especially in very hard games, this period is very entertaining, and in a sense it emulates the traditional feeling of flow, where a player is able to take on the hardest challenges without experiencing too much stress. Still, it won’t be long from the point the game gets easy that the player will become bored.
The most important take away from the essay is on the ideal S-curve for leveling. Basically summed up, level up fast in the beginning of the game to teach the mechanics of improving the character and also getting the player hooked on the anticipation of what is possible. Then the game should settle into a nice linear curve as the story progresses with a final acceleration towards the end. I can think of a lot of RPGs where the final hours of the story involve a dramatic exponential boost in the character’s levels, abilities, and power then a final challenge and a satisfying ending.