The main concept of my thesis was to plan and implement a strategy game in JAVA. This program is a Tower Defense game, in which the user's aim is to destroy all the enemy creeps, that are appearing on the map from time to time, and are controlled by the computer. To destroy these creeps, the user has to build and constantly upgrade different kind of towers from his/her money, which money is gathered by killing the creeps. There are multiple type of towers and creeps in the game. One of my goals during the semester was to reconsider, then rebuild my already written and documented software. After the full revision of my previous work, my task was to edit the plan, so that the system met the requirements of the new specification (and more). To test the changes and the whole program itself, I defined my own testcases. To maximize user experience I had to design and create an easy to use graphical user interface (GUI), after the implementation of the model was successful. To sum up and explain my work, I wrote this documentation.