[Inverness]

I use a world system on Valikorlia that specifies "worlds" as groups of levels depending on a level name prefix. The worlds are parsed in an order so you can specify more specific prefixes within broader ones. Each world has a name (displayed in upper right corner of screen), a level prefix, a color effect, a music filename, a boolean for if it is outside, a time offset, and a type.

The color effect is implemented using seteffect(). The outside boolean is used to determine whether or not to apply the day/night system. The time offset allows you to specify a difference for that world in the day/night system, so it might be nighttime in one area but midday in another. The type specifies what kind of weather would exist (and not fully implemented at the time). Certain level object classes will change their image depending on the world type, so they'll be snow-covered if it's winter.