The Conduit CYOA series is a set of worlds within a single framework, wherein players become "conduits", or beings akin to planeswalkers, traveling between different worlds. Unlike planeswalkers, however, conduits weaken the barriers between worlds simply by existing (as they "conduct" the fundamental nature of one world into others) creating bridges between the world where things seep through, usually to the detriment of whatever's on either side. Conduits also gain power from their worlds, channeling the fundamental essence of the world into their own selves. The full CYOA is available here: http://imgur.com/a/A25Uy and the creator takes the name Thrallherd when responding to discussion about it. An update is apparently in progress, but there is no solid ETA.
The Conduit CYOA revolves around a structure of worlds, each one having specific powers and themes.
Thrallherd has 'no problem' with fan-worlds that conform to the rules of the established universe and some have already been created by anonymous posters. Waifus and Husbandos for most of these worlds have been created.
The Conduit CYOA is also notable for its handful of spin-offs provided by third parties.
The conduit waifu CYOA allows conduits to pick a least conduit as a mentor, subordinate, and social companion. It is largely recognized as canon because Thrallherd included an option in the main CYOA referencing it obliquely. It is possible to spend one point of essence at character creation to attract a "mature conduit", implicitly one from the waifu CYOA. However, some people have argued that it clashes with canon as it references a Pontifex passing away shortly prior to the ascent of the player. Since the main CYOA describes the player as being among the first of the new conduits, and the ancient conduits were dead for a very long time, the origin of this pontifex is questioned.
There is a variant for fanworlds, one with men instead of women (and a fanworld expansion for that) and a version with powerful rivals rather than friendly characters.
The Queller CYOA pits the player as an antagonist to conduits. It stars the Shogun, a conduit with unusual powers not alluded to in the main CYOA. He grants the player a selection of powers designed to hunt and kill conduits, and the player will gain power from doing so.
It is thought that the Shogun's powers come in part from some virus-related world which the general community of conduits does not have access to. Many of the boons he grants his quellers are, however, are likely the result of considerable scientific research and development of materials and properties in more commonly accessible worlds.
Note that one point of essence as a conduit measures it is equal to ten points as a queller measures it, the "conduits you will be able to handle" which it references in the second paragraph are least conduits.
The original market casts you as an ordinary person, who has been invited to an extra-planar shopping city. All wares are things that it would be trivial for a conduit to purchase, and the funds allowed to the player are referenced as pocket change. Things that would be true prizes to conduits are presumably also sold here, but not listed due to a lack of relevance to the premise.
It seems that this world is likely a dedicated bevin created by some meister for the sole purpose of shopping. Thrallherd has said before that were there a market world (or a library world or other specific-purpose facility) it would take that form. Because this CYOA makes no alteration or assumption that doesn't fit within established canon, it's reasonable to consider it canon by default.
The second market CYOA deviates slightly from the original premise, although the main worlds clearly exist on Conduit worlds, not all the stops do and the railway isn't something that currently exists elsewhere.
The rim meister is a conduit that claims to want to help humanity. He lets you, as a native of this world, decide what kind of infused Serfs he should migrate to earth and how many. As a free source of labor Serfs will, according to him, make an end to hunger, poverty and injustice. A wise reader should be able to notice that a lot of possible combinations can only end in apocalyptic scenarios though. The CYOA makes a lot of assumptions on the nature of infused slaves, not alluded to by Conduit itself. Some fanworlds are acknowledged as extended universe in a little bonus image, however it is not consistently updated.
Rorch is a fanworld based on in-development third edition format. It has also been reinterpreted by somebody else as a standalone.
There are a few good stories based on the setting as well, so far showcasing conduits of individual worlds.