So... You like to read creepypastas don't you?
You like the idea of horror evolved, translated from campfires or dusty books in old dark basements at night into something you can tangibly browse on your computer in the depths of the night.
A creepypasta itself can appeal for the simple fact that it is something anyone could feasibly type up and post upon the web. With this in mind one could become the next Stephen King or H.P. Lovecraft based on a measly little tale or two. Unfortunately this is not the case, you are most likely to remain anonymous whether or not you do actually proceed to create an intriguing and widely circulating creepypasta. As such writing for fame or fortune is pointless.
There is of course only one reason to post a creepypasta, and that is simply to write a story, something to share to others in an age where online forums and the glow of a computer screen takes the place of a campfire gathering or a peculiarly quiet night in a dusty abandoned cellar.
Creating a believable atmosphere
It is vitally important to maintain the willing suspension of disbelief of your audience, otherwise the story itself will either be dismissed or worse ridiculed. This is perhaps the greatest pitfall of many "Most Dangerous Video game" stories as it is hard to find suspense or terror when even the narrator of the story himself is seemingly protected by the fourth wall. A much better option would be to instead consider a horror story in a more traditional real-time setting such as a group of friends visiting a local forest, waking up in an unfamiliar room, or a waking up from a disturbing vision...
Since the "haunted video game" and "lost episode" classes have been done to death there are various alternative settings you might want to consider. A demonstrative backstory takes the perspective of a character from a game itself, examining the events of the in-game world from their perspective, establishing a backstory for them, before eventually revealing who they are and their motivations within the game world. Traditional horror allows one the simple ability to imagine a psychological or cosmological horror story and post that over the web. For advice on these types of stories a simple look into the "How to Write a Horror Story" page would be recommended.
Making the protagonist relatable
If the protagonist isn't relatable, you usually end up not caring about them. This means that Mary Sue characters are even worse than usual, because nobody's perfect and that includes the reader. As such, you should give the protagonist flaws, interests, and redeeming qualities.