UPDATE 25/11/14 12.05pm Microsoft has confirmed that its recent surprise free gift of Limbo was sent to anyone who used their Xbox One during the console's launch weekend.
The platformer's new Xbox One port will be made available to purchase for everyone else "soon".
"We're looking forward to launching Limbo on Xbox One," a Microsoft spokesperson told Eurogamer. "As a thank you to our earliest adopters, fans who played their Xbox One the first weekend of launch received early, free access to the game.
"Limbo will also be available for purchase via the Xbox Game Store soon."
ORIGINAL STORY 25/11/14 08.35pm Microsoft has quietly released cult platforming hit Limbo on Xbox One, but - so far - it is only available for early adopters of the console.
An unknown number of Xbox One owners were messaged with a free code for the game over the weekend, as part of Microsoft's first anniversary celebrations.
The unannounced gift has so far not been mentioned on any of Microsoft's official channels. It's unclear how many copies were sent out, or what the requirements were to receive a free copy.
But, anecdotally, codes appear to have been sent to anyone with a Xbox One Day One achievement - which you were able to unlock by purchasing a "Day One" branded version of the console.
Limbo was showered with critical acclaim upon its original release for Xbox 360 back in 2010. It subsequently released on other formats, but its spiritual successor Inside - due next year - will also launch first on Xbox One.