Legend of the Black Rose is several things.
Now that that's out of the way, let's start work.
The home base of operations is a small civilized area outside of space and time known as Rosanegra. This place has a number of smaller local businesses that essentially provide supplies to the discerning adventurer, from weapons and armor to clothing and accessories. The one most relevant to adventurers is the Black Rose Inn.
The Black Rose Inn serves a number of basic purposes. For one, it's a place to save your game and your progress in safety - nothing will harm you in a Black Rose Inn room. For two, you can eat and drink in comfort and affordability, keeping your adventurer full and happy and ready to save the worlds. But most important, it has the Mirror.
The Mirror is a fairly simple interface - it has a keypad interface, which allows you to step through and transport from your current location to other connected Mirrors if you know the right passcode. The passcodes available change occasionally, and a list of public passcodes are listed beside the Mirror. If you're lucky, other Mirrors you find or emerge from might have similar public lists; otherwise, you'll have to guess and hope for the best. Passcodes may deliver you to wildly different places within a World, especially if you discover private passcodes, so keep your eyes out…
The savvy interdimensional traveler may note that not every passcode leads to the same place, even if it looks like it. That's because while the Mirrors connect to many different worlds, they also may connect to different instances of the same world. These instances are effectively variants of the same world - the people and places within may look the same, but things from the monsters you encounter to what's on sale at the stores will not, and there is always a chance that an instance will cease to exist at any given time. Instances that cease to exist will deposit characters still in them back into the Black Rose Inn, but it's worth noting before you get too invested in buying up local real estate or the like.
Each area where people can play, explore, fight, and make progress as adventurers is known as a World. Each World has its own struggles to overcome and its own evils to face. Each World also has an End Condition – a state in which, for good or for evil, the World's instance will end. Bringing a Good End to a World will affect future instances of a World in a positive way, while bringing a Bad End to a World will affect future instances negatively.
The starting World under development is Arcydea. The current play areas planned for Arcydea: