The areas of player modeling and adaptive systems are relevant to games by allowing the game to adapt itself to the player’s skill level, trying to offer a continuous challenge to the player, relative to its evolution in a way the player feels motivated to keep playing by the challenge proportional to his performance. The present work is a study on player modeling and dynamic difficulty adjustment, collecting data about games that use such concepts. An adaptive system based on player modeling is developed and tested with players to analyze the effectiveness and relevance of using such systems for maintaining the interest of the player, from the perspectives of the flow theory and the core elements of the gaming experience (CEGE) model.