It is a real thing and it appears to target game saves of popular games rather than all other files (may change or be incorrect though, not 100% on that). It appears to use the Angular Exploit Kit which is a web based attack. McAfee did a good write-up on the exploit vector if you're interested in how the infection portion works: Link (PDF File)
The actual payload itself is a standard encryption and demand payment of $1000 USD or 500 Bt Coins for a "promise" of the decryption key.
I can't really see many people paying the randsome though (probably why the price is very high). I know some people will be mad over losing a save but I don't see many people valuing them at $1000+
[Edited by Neo7, 3/15/2015 11:48:49 AM]
So from reading the attached link, if I use a script blocker on my browser (Adblock plus), ensure everything is up to date (OS and AV), and use good internet practices, I should be okay?
Pretty much, especially the "good internet practices part", most importantly, keep Brain.exe constantly updated to the newest version. It's the best security measure you have, especially when handling files on the Internet.
The "good practices" part is what took me a loooong time to teach my wife. She thought nothing of clicking on pop-ups and strange links. This is because, most Thai websites have some sort of pop-up ads, and or the link to the website is a shortened link that takes you to an ad before the actual webpage. Now that she understands about "Good Practices", she is almost maniacal in her exercise of it!