Emergent Complexity
The opposite of innate complexity (in which complex rules need to be learned in order to play) and a desired property of a game. Arises when you have a simple ruleset from which complex interations can arise.
Related to the idea of Emergent Gameplay in the context of strategy, another desired property of a game.
References:
- The Art of Game Design - A Book of Lenses (2nd Edition) (Chapter 13. Game Mechanics Must Be In Balance)