Currently, the interest in using serious games as a tool for learning and teaching in traditional educational processes has increased significantly. Therefore, serious games for learning are gaining increasing attention from researchers and domain experts (educators), as they are both looking for methods and tools to improve the quality of learning. Even though there are many existing design frameworks, models, and methodologies that offer valuable insights into the possibilities and limitations of serious games for learning, they focus mostly on high-level aspects and requirements of these games. Therefore, they do not fully help in understanding how such aspects can be concretely fulfilled. In this research, we investigate, characterize, and categorize the functional requirements and aspects needed for developing effective serious games for learning. This investigation aims to construct a conceptual framework to fill the gap in the current design frameworks. The proposed conceptual framework is used to understand the game´s structure and behavior with a focus on both aspects of serious games (educational and entertainment aspects), in other words, providing a way to think about the relationships between serious game components and the learning objectives of the game. The main contributions of the proposed conceptual framework are to facilitate and support the design and development process of these games as well as to enhance the collaborative work within a multidisciplinary development team. Finally, to show the feasibility and applicability of the conceptual framework, a practical example is presented to demonstrate the use of this framework. Furthermore, we conducted an evaluation process for implementing the conceptual model. The evaluation shows promising results in helping participants, particularly those with gaming experience, to understand and identify the roles of each component in the game and recognize the game's learning objectives. This will eventually lead to design and develop effective learning games in a flexible and easy-to-use way.