Why haven't they made/released a game that is what S.T.A.L.K.E.R. (will call it stalker from now on) was promised to be before stalker actually released?
If you don't know what I mean here's a really short re-cap:
Before stalkera actually released we got promises of a game with a game world that was "alive". This meaning that all NPC (enemies and friendlies alike) had the stuff to do and they would do them if not interupted by you, the player.
This in it self might not sound special in any way. The kicker is that stalker was supposed to be an open world game, this means that if you mucked around for to long without interupting NPCs (some more key than others) they would go about and finish their given objectives meaning you would lose the game while you where out just minding your own buissiness exploring some sewer or what ever.
This set up also meant that you potentially could "beat" parts of the game but not the "entire" game because the NPC might finnish some of their objectives, but not all, before being interupted by you.
Further this also promised some replayability since there would be multiple points within the game where you potentially could interupt the NPCs objectives meaning you could have your "boss" fight with some key NPCs fairly early on. Or you could have that fight right by some critical objetive point in the game.
The NPCs would also scavange the game for better gear and stuff meaning they would become more powerful the longer they would be allowed to roam the game world.