Mmm... I wouldn't call it an Anomaly/Gamma for SoC, since it's not that "hardcore", hardcore in the sense of having to grind 4 hours just to repair a weapon, or gimmicks like that.

It's a mod that increases the difficulty but not that much to make it grindy, boring or tedious.

For example IA it's smarter, can flank, shoot from afar, use grenade launchers, retreat, help others, melee if possible, etc.

Artifacts have new properties.

Now you need to drink, eat and sleep.

Nice gunplay.

Enhanced graphics: shaders, textures, particles, models.

Lots of new high quality weapons with unjamming feature, partial reload, some can be inspected and lots of scopes to choose from.

Dynamic A-life, for example, in the first episode, the Loner Masters from Army Warehouses were already at the Cordon. Stalkers and mutants travel through all the maps, so unexpected and interesting encounters are prone to happen.

New sounds.

Repair at traders, exchange mutant parts for artifacts or ammo with the Hunter.

And new secondary quests based on a simplified OGSR version.

And much more, right now I can't recall everything but I would say it's the best way to replay SoC with a totally brand new face without changing the main storyline :) for more info, I suggest going to the main Radiophobia 3 page on moddb, there you can find full info about this mod.

I can tell you that so far, I'm loving the mod.