While I can't do it in any of the languages you mentioned, I know a way to accomplish this affect with batch/DOS scripting, which more than satisfies your requirements. There's a program that can be called with certain parameters in DOS that can load a program in it's own separate date and time environment. Many utilize this to continue using trial software indefinitely, but could be tweaked to fit your purposes as well. If that idea doesn't work for some reason, there is a chance, like you said, that a save file, cache file, registry entry, etc, can be edited to change the time in-game, in which case I could still use DOS to automate this process for you. The only real time-consuming part of this will be the initial testing of how this game works and can be exploited,as I've never even heard of it. Software is software though, so it has to have a weak spot somewhere.