This is information regarding the tags associated with worlds in The End of All Worlds.
A World Derivative is the mark of how far from its original "parent" world it has traveled.

A Utopia world has gotten better than its parent world, improving the peace and prosperity of its inhabitants in some way or another. An example of this is the world Earth 1114, in which the 'Matrix' virtual reality unit went live and provided a comfortable and enjoyable world for all living humans, providing them with the challenges and opportunities they need to stimulate the mind and provide happiness in full truth. And the machines haven't needed to kill a single person to do it.

A Standard derivation is a world that is functionally the same, but has differences from the original that set it apart. These are often called Parallel Dimensions, as they are often extremely similar, minus a few key differences. Examples include Earth 8821, in which I am writing this from my home in New Hampshire (which in this world I've never even been to) because my parents moved east instead of west, became obscenely rich, and gave me the rights to do whatever I want. But, on the whole, the world isn't that different.
Also, there is Equestria 1773, In which the roles of Luna and Celestia are reversed, with the Daymare having been locked away for 1000 years and Luna ruling the land peaceably for those years, until the Elements of Harmony where used to redeem her as she returned from the sun, where she had been imprisoned. But the world is functionally the same.

A Distopian world has gotten worse for tis inhabitants, such as in Equestria 3357, in which Nightmare Moon overtook Celestia, killing her, and then shattered Discord's statue, killing him. In this world, Nightmare Moon has been a tyrant of the worst kind, forcing slavery and darkness on all her subjects, and making them live on the fungal life that has thrived in her eternal night.
However, that's a near worst-case scenario.

In a Dead world, all sentient life has been extinguished, and there is no source for it to come about. They are lifeless, and cannot sustain life in most cases.
the only recorded derivative that was registered as a Dead world reality was Marathon 0226, in which humanity had used a powerful weapon to disrupt all life-forces in the entirety of the universe, miscalculated, and wiped all possible life from their reality. Needless to say, this world is off limits.
Most Dead World realities are simply named with ID tags to show their lack of habitability.

A Horror derivative is one in which the worst has happened, or can happen at any time. Zombies, Thing Sentient Life Wasn't Supposed to Find Out About, and eternal legions of Lawyers haunt these worlds, making life a living hell in them. however, what marks out a world of this type is that the 'normal' inhabitants are strangely unaware of these possible horrors, and that the parent world has none of these horrors in it naturally, or to an extremely lesser extent. The world in which 'Cupcakes' takes place is one such world, in which the idea of Pinkie Pie being a terrifying psychopath actually happen. Another example are the worlds portrayed in most horror movies. In The Thing, there is a sentient being that infects and absorbs all life it encounters, slaughtering all it encounters.

Alternative derivatives are ones in which a key difference is made in a world, causing a ripple to form, that produces a new world.
Examples include so-called Gender-Bender worlds, which are the same as the parent, but with the flipped gender of noteworthy individuals. This causes the world to turn out much differently, as society has a way of making things that are remarkable for one gender impossible or commonplace for the other.
Another example is of a so-called If world, in which a possible difference is in place of what happened in the parent world, such as if the Americas had advanced in technology faster than Europe, and the native Americans had invaded Europe, rather than the other way around.
That world involves lots of Irishmen killing "injuns", and is a great vacation spot if you have a significant enough level of stealth to not get dragged into the fighting.

Parasite worlds are an anomaly, a type of world that latches onto another world and imposes some of its rules onto that world. The most prominent example of this is the Fae worlds, which have their own rate of time progression, steal beings from the worlds they attach to, and are usually much more magically adept than the worlds they attach to. Parasite worlds are considered very dangerous, and can often kill or enslave unwary travelers ensnared by the illusion of similarity to their host world.
A prime example of a parasite world that had invaded another universe is Draconequus, a which left a large group of its population spread across the timelines of the Equestria worlds. Most of these invaders have been imprisoned at this point, although some of the more altruistic denizens of the parasite world used the opportunity to escape, and assisted the worlds they encountered.

Unique is the descriptor for a reality that, for whatever reason, does not branch like the others. Instead of splitting off and creating alternates, it exists entirely on its own, with no derivatives, no alternates, no parallels whatsoever. So far, less than ten such worlds have been discovered that aren't parasite worlds, and each of these is a highly-classified secret, with the exception of Tchokisa, it being the "home" of this entire research staff, and indeed the primary fund supplier and founder of the largest interstitial exploration project currently know, other than the Endless Collective's dominion.

A world labeled as a Tech world is one in which there is no natural magic. while the world isn't necessarily hostile to magic, there's no natural wellsprings of magic on any level, resulting in a relatively rapid technological march, as there is less of the mystic in the world to distract from it. (but humans and other similar species are paranoid by nature, and tend to create superstitions even without good reason)
Some of these worlds are actively hostile to magic, draining or annihilating magic that dares encroach on the reality. These worlds often have advanced sciences early in their timelines, and sometimes kill themselves off.

An Apocalypse world is one in which the end of days has come, and gone. Most or all life in the world is dead, the afterlife(s) is(are) packed, and there's usually lots of raw minerals exposed and available. Lots of ruins, too. Earth 28947 bombed itself into this state.

there are more, and will be added as necessary. If you wish to designate a character to have been from a particular derivative type, please say so when submitting the character.