This article explores the use of mobile phones for educational purposes through the design, development and evaluation of Role Playing Games (RPG). To accomplish this, we differentiated between the functionality and design of the videogame, developing a videogame engine and videogames prototypes. Thus the engine was responsible for controlling the videogame's functionalities regarding the prototypes designed. Once designed and developed, a usability evaluation of the videogames with end-users was administered. Results show that the videogames implemented were usable, easy and pleasant to use, and that they fully motivated learners as mobile learning tools.