I just got S.T.A.L.K.E.R. SoC off of Steam as a recommendation from a friend. I didn't see much of the game prior to buying it, but it sounded interesting enough to buy it. Upon playing, I realize how great the world looked. It's kinda hard to explain, but it just had this saturation and atmosphere that made it stand out and look impressive (it's a very well optimized game as well, on an unrelated note). I had to just wander around for a couple of minutes to really soak in the environment. Added to the effect of wandering into the anomalies just added to atmosphere. So what games can you categorize as "good looking without good graphics"?