With the development of the Internet and Web technology, HTML5 specification is supported and recommended by the W3C and the mainstream Internet in the world as the new standards of the Web application development of the next generation. The function of HTML5 is also refined and stabilized, at the same time HTML5 has many new attractive features. With the canvas tags, HTML5 can dynamically generate kinds of graphics and animation, and has been fully equipped with the basic conditions designing games. In this paper, the design scheme of a little WeChat game based on HTML5 called telepathy is provided, which has combined the function of canvas and the algorithm of the polygon area.