With the evolution of the gaming industry, there is an increasing demand for games that offer immersive experiences beyond basic gratification. Traditional games with fixed difficulty levels often fail to cater to the diverse preferences and skills of players. To address these needs, dynamic difficulty adjustment (DDA) has emerged as a crucial element in game design. This review explores the application of Deep Reinforcement Learning (DRL) in achieving DDA, contrasting it with traditional methods. By examining various DRL algorithms and their effectiveness, as well as evaluating traditional models, this review identifies the potential of DRL in enhancing player experiences and outlines existing challenges. It also highlights future research directions, including the integration of DRL with Flow Theory and innovative evaluation methods. The goal is to provide a comprehensive overview of how DRL can advance game design and improve player satisfaction.