As Lady Emz has said, people have been using this method with our games since the PDA days. We don't recommend it, because it does affect everything on your computer, including the operating system, the file system, email, anti-virus and other time-based applications. I have a special computer that I don't care about to do this kind of thing during testing, but I NEVER adjust the system clock on any of my other computers. It's just not wise to do that simply to make a game go faster.