The broad objective of the thesis is make implementation of CityScrabble, a network multiplayer game, for mobile devices based on the Android platform, using the programming language Java for Android. The specific objectives of this study were outlined as follows: a) To improve the communications protocol. b) To make the design, interface and the user interaction better. c) To correct errors in the last game. d) To implement new features. e) Evaluation session The idea to develop this game begins in a previous game that was developed by Diego Rodriguez Puerto, a student from University of Valladolid. He implemented the game using a Web service based on REST architecture, so the main aim of my project was replace the existing protocol and implement XMPP. It is an open and extensible protocol based on XML, originally designed for instant messaging. This is the protocol selected for Google messaging service Google Talk, Facebook and Myspace and other for chat. For this, I have integrated a Smack library that allows connecting, sending and receiving messages between the players’ devices and XMPP server. The most important reason why it was decided to change the protocol of the game is that if we have more than one scenario (more than a group of People playing CityScrabble at the same moment), we need to create another chat room in the server in order to differentiate between different kinds of games that are being run on the same server. In order to improve the design, as the last interface was adequate and worked property, some parts have been modified to optimize the game and make it more intuitive. A login screen, a progress dialog, a new toggle button and toasts have been integrated to correct errors in the system and improving the Diego Rodriguez version. Others objectives were also correct errors in the last application and implement new features. Some of these features have been proposed is the method of unlocking the game elements using GPS integrated in Android devices, a new login design that allows create and join games, different options depending of the scenario and program a real communications server. After completing the application, we have prepared an evaluation session in a real scenario with a group of people in order in order to see if the end user like the application has been designed and consider proposals to improve it in the future. / -