By their very nature video games are a more wide-open media form than, say, movies, TV, or books, with players able to explore and absorb every last inch of their expansive worlds.
And so it's little surprise that developers often like to reward curious players with Easter eggs and hidden references which would be easily missed by "critical path" players.
But sometimes they decide to go further and insert messages into their games which are a little more abstract, defying easy categorisation and, in extreme cases, bugging the fanbase for years if not decades.
These 10 video games all featured secret messages which were eventually unearthed by attentive players, and despite dogged investigation online, there hasn't ever been a concrete explanation of their meaning.
Though in some cases there have been plausible deductions from the fanbase, the undeniable, crystal clear meaning of the messages themselves remains most frustratingly up in the air.
Given the sheer amount of time that's passed in some cases, it's probably best for fans to just accept that they're never going to be solved beyond all doubt...
10. Blue Creek Whispers - Silent Hill 2
Because the Silent Hill games aren't creepy enough already, Konami decided to bamboozle players with a spine-tingling mystery which still remains unsolved to this very day.
In the second game when visiting room 209 in the Blue Creek Apartments, keen-eared players might hear a faint, scarcely intelligible voice whispering to them.
Fans have spent hours listening to the message literally hundreds of times in an attempt to decipher it, but even today there's no clear consensus on what's being said or why it's in the game.
The most common opinion is that the voice says, "See my dead wife, come home to do some laundry to escape...," though that deduction is very far from conclusive.
In an interview, the game's creative consultant Jeremy Blaustein believed the speech was nothing more than gibberish spoken during one of the game's recording sessions.
More recently, however, it was discovered that the whisper was actually taken from a stock sound library, Nightingale Voice Box Sound Effects Library Volumes 1 & 2, though even a high-quality sample makes it no easier to understand what's being said (or isn't).
The whispers clearly weren't made exclusively for Silent Hill 2, but their precise meaning still remains very much up in the air.