Yeah if you come from modded Anomaly S2 will feel downright casual, but it's not even necessarily the challenge that would turn off mainstream players though I think but the pace. Stalker has always been a very slow game (and we love it for it!), but that's a tough product to sell in today's attention economy.

On a side note, if you're into GAMMA etc and truly hate yourself you can check out Stalker A.R.E.A.. I was playing around with it a bit just before the release of S2. Disgusting stuff.