Book excerpt: Everyone plays games! However, it is often to see some of people have difficulty playing games together. This is an opportunity for game designer to enrich the game market. However, I know of no established game design principles can help game designers to address this need. The goal of universal design is to build a design that is inclusive and can broaden the end user audience, which is similar with to the need for multiplayer game design. This thesis proposes that by applying universal design principles to the multiplayer game design process can make the game playable and enjoyable for a wilder range of players. This thesis will give an explanation to why some of the players with different skill sets are unable to be fully engaged while competing against each other. I will be analyzing this using Flow theory. A variety of case studies will be conducted to explore the current inclusive games and estimate the significance of universal design principles in these games. Then a multiplayer game design will be developed using universal design principles and other findings to address inclusivity issues for players with differing skill sets.