Stalker 2012 is the Stalker 2 that was cut in 2012, basically, while COP was in the making and released GSC were pre-producing their Stalker 2, however, this was cancelled in 2011-2012 when GSC shut down effective. The Stalker 2 we have nowadays is completely different from Stalker 2012, from tone to art-style, despite Stalker 2 having lifted a lot of concepts. Basically, Stalker 2 aimed to make the zone a lot more sci-fi in nature and a lot more inspired by Roadside Picnic, having the dillema of the game be literally about privatising the wealth of the zone or not, the factions all followed this theme as well allowing you to solve their internal problems in a way to keep their identity or have them join a government institution to keep the theme of the gov controlling the zone.
I used to play stalcraft for a summer, the first half of the game is fun, if you have friends then it will be even better, however, as soon as you make it to the north it drops the ball hard as it expects you to do copious ammounts of grind that can be expedited with cash, meanwhile pushing you to do PVP shit with clans and teams, which if you don't speak russian or play Stalcraft as your main game, good luck keeping on.