GoldSrc Engine (Counter-Strike/Counter-Strike: Condition Zero/Day of Defeat/Deathmatch Classic/Ricochet/Team Fortress Classic)
Source Engine (Counter-Strike: Source/Day of Defeat: Source/Half-Life 2: Deathmatch/Half-Life Deathmatch: Source/Team Fortress 2)
Awesomenauts
Chivalry: Medieval Warfare
Dota 2
Loadout
Nether
Insurgency

Counter-Strike: Global Offensive
Tactical Intervention (According to developer/Unlisted)

21 Days
Awesomenauts
Block N Load
Counter-Strike: Global Offensive
Don't Knock Twice
Football Manager 2018
Paladins
PAYDAY 2
PLAYERUNKNOWN'S BATTLEGROUNDS
Shoot Paint
Steam Discussions
Tactical Intervention