Choosing a wiki software

I am currently looking for a wiki software to use.

My should-requirements are:

• Uses PHP
• Simple to set up and administrate
• Syntax similar to MediaWiki
• Doesn't use databases besides MySQL and MongoDB

My can-requirements are:

• Possible to hack in a way that it can share user accounts with my game

MediaWiki

My first idea was the popular MediaWiki, but the "What is MediaWiki" section on their homepage says: 

"MediaWiki is geared towards the needs of the Wikimedia Foundation. The program is primarily developed to run on a large server farm for Wikipedia and its sister projects. Features, performance, configurability, ease-of-use, etc are designed in this light; if your needs are radically different the software might not be appropriate for you." 

I just want a wiki for my small little game, not build a million-article encyclopedia running on a dedicated server-farm, so this doesn't really sound like the right software for me.

PmWiki

The second software which caught my eye was PmWiki, pretty much the Anti-MediaWiki.

It is extremely simple to set up, because it doesn't even require a database. It saves everything in flatfiles. This might look strange in this day and age, but they are making a convincing argument. I tried it and the installation was indeed a breeze - just copy the PHP-files and it runs out-of-the-box.

But what really surprised me is that PmWiki by default does not even know the concept of personalized user accounts. In the default configuration, everything can be edited anonymously. When you don't like that, you can set individual passwords, but they are not bound to accounts. Anyone who knows the password can read or edit specifically protected pages.

There are, however, lots of addons which enable mandatory logins with username and password. Many of them are designed to use the user databases of other systems. That likely means that I could write my own which uses the accounts in my MongoDB.