Inhaltsangabe: Abstract: This report describes the development of a class library, designed as a tool to produce twodimensional games while making use of up-to-date 3D technology. The design and implementation of each library component, such as graphic, sound, sprites or collision detection, is described. There is a special focus on collision detection algorithms in a hybrid 2D / 3D environment. The report starts with an introduction which states the reasons behind the project and lists the project's objectives. The main section consists of two parts. In the first part, technology choices, the project time schedule and the development process are discussed. The second part describes the important library classes one by one. The larger sections start with an analytical part, proceed with an implementation description and close with an evaluation regarding the particular class. Finally, the project is reviewed, comparing the outcome to the project plan and the project's overall objectives. A summary is given of what I have learnt in the course of the project, and the report ends with a brief outlook on the project's future possibilities. Although the production of two-dimensional games has gradually phased out over the past few years, there has been a revival movement. Especially with the introduction of more capable hand-held devices, such as palm-tops or mobile phones, old ideas are recycled and ancient games are brought to new life under the label of retro-style'. I thought it would be interesting to develop a tool that enables people to recreate games of the past while making use of up-to-date technology. Another, more personal reason is, that more than a good CV, many companies in the game industry like to see a skill demonstration before they hire. Grown up with a passion for games, I thought this would be a good chance to familiarise with relevant technologies and make another step towards developing games professionally. Zusammenfassung: Lean & Mean ist eine S"