"Level progression" refers to the gradual advancement or improvement in a video game or similar activity by moving on to increasingly difficult or challenging levels. Full definition
A randomized / procedural level progression system that provides a different journey each time you play. (cultureofgaming.com)
Yet the idea of level progression isn't really expressed clearly enough. (thekoalition.com)
I see myself going back often to multiplayer, not just for level progression, but because they are so chaotic, unpredictable and they last a good long while. (darkstation.com)