grosbouff

Pencil Wiki is a simple wiki solution for your WordPress.
Basically, it adds new roles & capabilities that allow your users to add/edit wiki pages (custom post type).
It comes with several widgets and custom templates (that you can override) fully integrated with the Twenty Twelve theme.
Pages are edited backend, but there is a menu on every wiki page with the necessary links; and a wiki index / search input.
Only Administrators and Editors can create new wikis (top-level pages); and Wiki Authors can add pages to it. 
Administrators and Editors can also LOCK some wiki pages (for any reason) or branches; which means they will not be editable anymore by other users.
I voluntarily made the plugin quite simple to avoid making it intrusive (javascript, css, …) and put too many features. I recommend to run it with those plugins : 
* <a href="https://wordpress.org/extend/plugins/member" rel="ugc">Members</a>Members by Justin Tadlock, to manage roles and capabilities 
* <a href="http://mtekk.us/code/breadcrumb-navxt" rel="nofollow ugc">Breadcrumb NavXT</a> by John Havlik, to generate breadcrumbs 
* <a href="https://wordpress.org/extend/plugins/simple-footnotes" rel="ugc">Simple Footnotes</a> by Andrew Nacin, to put footnotes in your wiki pages.
WordPress has a revision system, which is perfect for a wiki. 
Unfortunately, I didn’t find a way to customize it (add revision messages, etc).

Pencil Wiki

Pencil Wiki is a simple wiki solution for your Wordpress.

dmccan

simplyletgo

Yada Wiki provides a wiki post type, custom tags and categories, an index, and a table of contents option. The plugin allows you to link your wiki pages together using the wiki page titles.
Note: As of Yada Wiki 3.6, for current users who have been manually adding HTML tags or special characters to their shortcodes, for security reasons these must be filtered on save. An exception was added for the EM tag because I saw support tickets where users said they were using this tag. If you have been manually editing the shortcodes then you may want to test before installing version 3.6.
There are two easy to use shortcode buttons available on the editor toolbar. Rather than try to remember the shortcodes and their values, it is recommended that you use these buttons to generate the shortcodes for you.
The “Add Wiki Link” Button: 
When you click the first button, the add wiki link button, a pop-up opens where you enter the title of the wiki page you are linking to in the “Link” text box. You can optionally enter text into the “Show” text box that you want to show for the link, or leave that blank to just show the title. There is the ability to manually add an “anchor” parameter for on-page links. Please see the documentation for more information on this.
When you click “OK”, a shortcode is inserted into your edit window at the cursor location. For example to link to a wiki page called “How To Make Iced Coffee” but show the text for the link as “How To Make My Favorite Drink”:
[yadawiki link=”How To Make Iced Coffee” show=”How To Make My Favorite Drink”]
You use Wiki Link shortcodes to create the structure of linked pages.
The “Add Wiki Listing” Button: 
The Add Wiki Listing button gives you three options for adding some collected output.
Output TOC Page 
The first option inserts a shortcode that will output your “TOC” page. With Yada Wiki, you can create a special wiki page with the title of “TOC” that will serve as the table of contents for your wiki. You can use wiki links and style the table of contents as you like in the post editor. Selecting this option allows you to embed the TOC page in another page. For example:
[yadawikitoc show_toc=”true”]
Output Wiki Category 
The second option inserts a list of the wiki pages for one of your wiki categories. You can optionally choose to output the list by title or by creation date. For example:
[yadawikitoc show_toc=”true” category=”Drinks” order=”title”]
Output Index 
The third option inserts a grid of your wiki pages or categories. The output is in a responsive table-like grid and you can choose the number of columns. For example, to output wiki pages:
[yadawiki-index type=”pages” columns=”4″]
An example for listing a single wiki category by title:
[yadawiki-index type=”category-name” category=”States” columns=”3″]
An example for listing all wiki categories by title:
[yadawiki-index type=”all-categories-name” columns=”3″] 
Note that in the index listing the category hierarchy only goes down one level deep from to the top.
Sidebar Widgets: 
There are two Yada Wiki widgets. One for showing the TOC page and a list of article titles for a given category in the sidebar and the other for showing recent wiki articles. Please see the FAQ section for information about using the sidebar widgets.
Documentation: 
Documentation is available at https://www.webtng.com/yada-wiki-documentation/
The FAQs below also have good information.
Video Walk-through: 
This video provides a walk-though of all of the features:
<iframe loading="lazy" title="Yada Wiki Plugin for WordPress" width="750" height="422" src="https://www.youtube.com/embed/yixVePH3IpA?feature=oembed" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
** Translations ** 
The plugin is available in: 
* English 
* Spanish
<h3>Acknowledgements</h3>
The user @JulianSMoore has been very helpful in suggesting improvements and reviewing changes. Thanks to the user @simplyletgo who contributed the recent wiki post widget.

Yada Wiki

I found it simple and intuitive to set up a wiki for my D&D group.

Easy to get started, works great

Yada Wiki is a simple wiki for your WordPress site.

Pencil Wiki vs Yada Wiki