You all know fiction. You experience it every day, on many different platforms. Books, movies, and now, YouTube and Twitter.
ARGs, or alternate reality games, are usually horror-focused content that is most prevalent on YouTube, but it has also been popping up on Twitter too.
Usually shot like Paranormal Activity, the point of ARGs is that you're not supposed to know they're fake. They're staged like real YouTube channels and Twitter accounts, documenting whatever the creators want to document. After a few "normal videos" that is, they start to get... weird. That's all I'm going to say on it though.
Interested? Check out the YouTube channel NightMind. Not only does he streamline content (so you don't have to spend a million hours watching filler videos) but he explains it! My favorite ARGs are AlanTutorials and EverymanHYBRID.
Be warned though, these videos are horror. There are monsters, jumpscares, and people dying, all in a very real sense. However, if you're tired of all the horror movies coming out nowadays, ARGs are a new, and very scary, platform.