The game engine stats outlines the most popular game servers

Game Name Engine
Game Name Engine
7 Days to Die Unity 3D
Action Half-Life Gold Source
Action: Source Source
ARK: Survival Evolved Unreal 4
ARMA 3 Real Virtuality 4
Ballistic Overkill Unity 3D
Barotrauma None
Base Defense Gold Source
Battalion 1944 Unreal 4
Battlefield 1942 Refractor
Black Mesa: Deathmatch Source
Blade Symphony Source
Brainbread Gold Source
BrainBread 2 Source
Call of Duty idtech3
Call of Duty 2 iw2.0
Call of Duty 4 iw3.0
Call of Duty: United Offensive idtech3
Call of Duty: World at War iw3.0
Codename CURE Source
Counter-Strike 1.6 Gold Source
Counter-Strike: Condition Zero Gold Source
Counter-Strike: Global Offensive Source
Counter-Strike: Source Source
Day of Defeat Gold Source
Day of Defeat: Source Source
Day of Infamy Source
Deathmatch Classic Gold Source
Don't Starve Together Don't Starve Together
Double Action: Boogaloo Source
Dystopia Source
Eco Unity 3D
Empires Mod Source
ET: Legacy idtech3
Factorio Factorio
Fistful of Frags Source
Garry’s Mod Source
GoldenEye: Source Source
Half-Life 2: Deathmatch Source
Half-Life Deathmatch: Source Source
Half-Life: Deathmatch Gold Source
Hurtworld Unity 3D
Insurgency Source
Insurgency: Sandstorm Unreal 4
IOSoccer Source
Just Cause 2 Avalanche
Just Cause 3 Avalanche
Killing Floor Unreal 2
Killing Floor 2 Unreal 3
Left 4 Dead Source
Left 4 Dead 2 Source
Medal of Honor: Allied Assault idtech3
Minecraft lwjgl2
Mordhau Unreal 4
Multi Theft Auto Renderware
Mumble None
Natural Selection Gold Source
Natural Selection 2 Spark
No More Room in Hell Source
NS2: Combat Spark
Nuclear Dawn Source
Opposing Force Gold Source
Pirates, Vikings, & Knights II Source
Post Scriptum Unreal 4
Project Cars Madness
Project Zomboid Project Zomboid
Quake 2 idtech2
Quake 3: Arena idtech3
Quake Live idtech3
Quake World quake
Red Orchestra: Ostfront 41-45 Unreal 2
Return to Castle Wolfenstein ioquake3
Ricochet Gold Source
Rising World Risingworld
Rust Unity 3D
San Andreas Multiplayer Renderware
Serious Sam 3: BFE Serious Engine 3.5
Soldat None
Soldier of Fortune 2: Double Helix Gold idtech3
Source Forts Classic Source
Squad Unreal 4
Starbound Starbound
Stationeers Unity 3D
StickyBots Unreal 4
Sven Co-op Gold Source
Team Fortress 2 Source
Team Fortress Classic Gold Source
Teamspeak 3 None
Teeworlds Teeworlds
Terraria Terraria
The Specialists Source
Tower Unite Unreal 4
Unreal Tournament 2004 Unreal 2
Unreal Tournament 3 Unreal 3
Unreal Tournament 99 Unreal
Unturned Unity 3D
Vampire Slayer Gold Source
Warfork Qfusion
Wolfenstein: Enemy Territory idtech3
Wurm: Unlimited None
Zombie Master: Reborn Gold Source
Zombie Panic! Source Source