7 Days to Die
BioShock 1 + 2
Dead Space 1 + 2
Deus Ex GotY (preferably with Revision)
Dishonored
Divine Divinity
Fallout 1 + 2 + 3 + New Vegas +4 (all modded)
FEAR (the first was the best)
Grim Dawn
Hard Reset
Lord of the Rings: War in the North
Metro 2033 + Last Light
Sniper Elite V2 + 3 + 4
STALKER (series and Radiophobia standalone mod)
STALKER Anomaly (unbelievably good non-Steam standalone mod)
Witcher (series)
Zombie Army 1 + 2 + Trilogy