World tweets a mysterious image that seems related to
their plans for S.T.A.L.K.E.R. 2
(thanks Rhialto). This is an image of the number 35, and the accompanying tweet
says this mystery is already partially solved:
It's a fantastic game that's well worth playing, but I'd recommend getting the Complete mod. It really fixes everything that was lacking in the base game, from bugs, quality of life improvements, to better graphics and weather effects.