If you see S.T.A.L.K.E.R. on sale over the holidays, it's well worth playing. Search for the S.T.A.L.K.E.R. Complete mod pack before you play; it offers a pretty good graphical upgrade.

The game is a slow burn at first. It's a pretty open world, and despite the fact it appears like an FPS game, there's a RPG feel as well. Lots of conversations, quests, factions, and exploring the world around you.

The more time you put into playing, the more the world rewards you. Don't be afraid to look up walkthroughs or tips if you get stuck; it's the kind of game that might be confusing without little yellow question marks over NPC heads, but there's always a solution for the challenges you face.