SimPlay runs inside your Web browser. Ths Flash Player plugin (version 9 or greater) is required to make use of SimPlay. You certainly already have it, as a lot of web sites (Youtube, Dailymotion, ...) use Flash to playback their videos.
If Flash is not installed on your computer, go to the Adobe web site and follow the installation instructions.

SimPlay has been successfully tested on the three main operating systems (Linux, MacOS X and Windows).