10. A Real-Life Treasure Hunt...Which Won't End Until 2113 - Trials Evolution
Though the Trials franchise is known for its controller-smashing physics-based difficulty, who could've possibly expected that the most challenging task would send players on a real-life fetch quest?
When Trials Evolution was released in 2012, fans knew to keep their eyes and ears peeled for Easter egg riddles, as were abundant in the prior Trials HD, but nothing prepared them for the rabbithole they'd fall down unlocking Evolution's big secret.
A series of planks located throughout the game spelled out a cipher, which instructed players to perform a specific move on their bike, which then unlocked a hidden song, within which a secret Morse code was embedded.
The Morse code led to a website which revealed a series of image ciphers and an equation, which fans quickly figured out, and this is where things got really wild.
The answer to the equation unlocked a series of co-ordinates in real world cities - Helsinki, Sydney, Bath, and San Francisco - prompting fans to visit these locations and snoop around.
In each of the four locations - including a graveyard in Bath and a literal hole in the ground in San Francisco - a small chest containing a key was discovered along with a plaque. The back of each plaque read, "Midday in Year 2113. 1st Sat in Aug One of Five keys will open the box Underneath the Eiffel Tower."
That's right. Developer RedLynx has made arrangements for one of the keys to open a box underneath the Eiffel Tower more than 100 years after the game was first released, whereby all of the key's recipients and anyone who had a hand in developing the game will likely be long dead.
And if you're wondering about the fifth key mentioned on the plaque, it actually turned out to be a digital key unlocked in the sequel, Trials Fusion.
For a more comprehensive account of the insane treasure hunt from those involved, take a gander over at Kotaku.