// dot -o engine.svg -Tsvg engine.dot
digraph {
	ratio=auto;
	ranksep=1.5;

	// =============================
	// Engines
	// =============================
	node [shape=polygon, sides=6, style=filled]

	// id Tech engines
	node [peripheries=4, size=6]
    fontsize=20
	// id Tech engines under GPL
	node [fillcolor=lightgreen]
    //Quake
	QuakeE [label="Quake engine"]
	GLQuake
	WinQuake
	QuakeWorld

	Quake2E [label="Quake II engine"]
	idTech3 [label="id Tech 3\nQuake III Arena engine"]
	idTech4 [label="id Tech 4\nDoom 3 engine"]

	// id Tech under commercial license
	node [fillcolor=lightgrey]
	idTech5 [label="id Tech 5"]
	idTech6 [label="id Tech 6"]
	idTech7 [label="id Tech 7"]
	idTech8 [label="id Tech 8"]

	// Other engines
	//
	node [peripheries=1]

	// Other commercial engines
	node [fillcolor=lightgrey]
	GoldSrc
	Source [label="Source Engine"]
	sourcemp [label="Source - Multiplayer"]
	sourcel4d [label="Source - Left 4 Dead"]
	sourceas [label="Source - Alien Swarm"]
	sourceportal2 [label="Source - Portal 2"]
	titanf [label="Source - Titanfall"]
	sourcecsgo [label="Source - CS:GO"]
	sourcedota2 [label="Source - Dota 2"]
	Source2 [label="Source 2"]

	IW2 [label="IW 2.0"]
	IW3 [label="IW 3.0"]
	IW4 [label="IW 4.0"]
	IW5 [label="IW 5.0"]
	IWBO2 [label="Black Ops II engine"]
	IW6 [label="IW 6.0"]
	SHG [label="Sledgehammer Games engine"]
	IWBO3 [label="Black Ops III engine"]
	IW7 [label="IW 7.0"]
	IWBO4 [label="Black Ops 4 engine"]
	IW8 [label="IW 8.0"]
	IWBOCW [label="Black Ops Cold War engine"]
	IW9 [label="IW 9.0"]

	Void [label="Void Engine"]

	Motor

	// Other libre/open engines
	node [fillcolor=lightgreen]
	DarkPlaces
	ioquake3
	ioUrbanTerror

	// =============================
	// Games
	// =============================
	node [shape=ellipse, color=transparent]

	// Commercial Games
	node [fillcolor=lightgrey]
	// id and Bethesda
	HexenII [label="Hexen II"]
	Malice
	xmen [label="X-Men: The Ravages of Apocalypse"]
	laserarena [label="Laser Arena"]
	wrathaor [label="Wrath: Aeon of Ruin"]

	HereticII [label="Heretic II"]
	SiN
	KpLOC [label="Kingpin: Life of Crime"]
	sof [label="Soldier of Fortune"]
	daikatana [label="John Romero's Daikatana"]
	Anachronox

	stvoyager [label="Star Trek: Voyager - Elite Force"]
	returntowolf [label="Return to Castle Wolfenstein"]
	sofII [label="Soldier of Fortune II: Double Helix"]
	swjkiijo [label="Star Wars Jedi Knight II: Jedi Outcast"]
	swjkja [label="Star Wars Jedi Knight: Jedi Academy"]
	QuakeLive [label="Quake Live"]

	Quake4 [label="Quake 4"]

	Rage
	WolfensteinTNO [label="Wolfenstein: The New Order"]
	WolfensteinTOB [label="Wolfenstein: The Old Blood"]

	Dishonored2 [label="Dishonored 2"]
	Deathloop

	Doom2016 [label="DOOM(2016)"]
	Wolfenstein2 [label="Wolfenstein II: The New Colossus"]
	WolfensteinYB [label="Wolfenstein: Youngblood"]

	DoomEternal [label="DOOM Eternal"]

	TheGreatCircle [label="Indiana Jones and the Great Circle"]

	DoomTheDarkAges [label="DOOM: The Dark Ages"]

	// GoldSrc & Source
	HL [label="Half-Life"]
	TFC [label="Team Fortress Classic"]
	CS [label="Counter-Strike"]
	DoD [label="Day of Defeat"]
	CSCZ [label="Counter-Strike: Condition Zero"]
	CSO [label="Counter-Strike Online"]

	CSS [label="Counter-Strike: Source"]
	HL2  [label="Half-Life 2"]
	HL2DM [label="Half-Life 2: Deathmatch"]
	DoDS [label="Day of Defeat: Source"]
	HL2ep1 [label="Half-Life 2: Episode One"]
	gmod [label="Garry's Mod"]
	HL2ep2 [label="Half-Life 2: Episode Two"]
	l4d [label="Left 4 Dead"]
	l4d2 [label="Left 4 Dead 2"]
	AS [label="Alien Swarm"]
	portal [label="Portal"]
	portal2 [label="Portal 2"]
	HLA [label="Half-Life: Alyx"]

	Titanfall
	titanfall2 [label="Titanfall 2"]
	
	COD [label="Call of Duty"]
	COD2 [label="Call of Duty 2"]
	COD4 [label="Call of Duty 4: Modern Warfare"]
	CODWAW [label="Call of Duty: World at War"]
	CODMW2 [label="Call of Duty: Modern Warfare 2"]
	CODBO [label="Call of Duty: Black Ops"]
	CODMW3 [label="Call of Duty: Modern Warfare 3"]
	CODBO2 [label="Call of Duty: Black Ops II"]
	CODG [label="Call of Duty: Ghosts"]
	CODAW [label="Call of Duty: Advanced Warfare"]
	CODBO3 [label="Call of Duty: Black Ops III"]
	CODIW [label="Call of Duty: Infinite Warfare"]
	CODMWR [label="Call of Duty: Modern Warfare Remastered"]
	CODWWII [label="Call of Duty: WWII"]
	CODBO4 [label="Call of Duty: Black Ops 4"]
	CODMW [label="Call of Duty: Modern Warfare"]
	CODMW2CR [label="Call of Duty: Modern Warfare 2 Campaign Remastered"]
	CODBOCW [label="Call of Duty: Black Ops Cold War"]
	CODV [label="Call of Duty: Vanguard"]
	CODMWII [label="Call of Duty: Modern Warfare II"]
	CODMWIII [label="Call of Duty: Modern Warfare III"]
	CODBO6 [label="Call of Duty: Black Ops 6"]
	
	// Freeware games
	node [fillcolor=lightblue]
	alienarena [label="Alien Arena"]
	urbanterror [label="Urban Terror"]

	TF2 [label="Team Fortress 2"]
	CSGO [label="Counter-Strike: Global Offensive"]
	dota2 [label="Dota 2"]
	apex [label="Apex Legends"]
	CS2 [label="Counter-Strike 2"]
	Deadlock

	CODWZ [label="Call of Duty: Warzone"]
	CODWZ2 [label="Call of Duty: Warzone 2.0"]
	CODWZM [label="Call of Duty: Warzone Mobile"]

	// Libre/open games
	node [fillcolor=lightgreen]
	Quake
	Nexuiz
	Xonotic

	QuakeII [label="Quake II"]
	ufoai [label="UFO: Alien Invasion"]
	gravitybone [label="Gravity Bone"]
	thirtyfol [label="Thirty Flights of Loving"]

	QuakeIIIArena [label="Quake III Arena"]
	wolfet [label="Wolfenstein: Enemy Territory"]
	OpenArena
	Tremulous
	smokinguns [label="Smokin' Guns"]
	wop [label="World of Padman"]

	Doom3 [label="DOOM 3"]
	
	// =============================
	// Trees
	// =============================

	QuakeE -> Quake2E -> idTech3 -> idTech4 -> idTech5 -> idTech6 -> idTech7 -> idTech8

    QuakeE -> {WinQuake,GLQuake,QuakeWorld,DarkPlaces}
	QuakeE -> {Quake,HexenII,laserarena,wrathaor}
    {QuakeWorld,GLQuake,WinQuake} -> Quake
	Quake -> {Malice,xmen}
	DarkPlaces -> {Nexuiz,Xonotic}

	Quake2E -> {QuakeII,HereticII,KpLOC,SiN,sof,daikatana,Anachronox,ufoai,gravitybone,alienarena}
	gravitybone -> thirtyfol

	idTech3 -> {QuakeIIIArena,COD,QuakeLive,stvoyager,returntowolf,sofII,swjkiijo,swjkja}
	idTech3 -> {ioquake3,IW2}
	returntowolf -> wolfet
	ioquake3 -> {OpenArena,Tremulous,smokinguns,urbanterror,wop,ioUrbanTerror}
	ioUrbanTerror -> urbanterror

	IW2 -> IW3 -> IW4 -> IW5 -> IW6 -> IW7 -> IW8 -> IW9
	IW3 -> IWBO2 -> IWBO3 -> IWBO4 -> IWBOCW
	IW5 -> SHG 
	COD -> COD2 -> COD4 -> CODWAW -> CODMW2 -> CODBO -> CODMW3 -> CODBO2 -> CODG -> CODAW -> CODBO3 -> CODIW -> CODWWII -> CODBO4 -> CODMW -> CODBOCW -> CODV -> CODMWII -> CODMWIII -> CODBO6
	CODMWR -> CODMW2CR
	CODWZ -> {CODWZ2,CODWZM}
	IW2 -> COD2
	IW3 -> {COD4,CODWAW,CODBO}
	IW4 -> CODMW2
	IW5 -> CODMW3
	IWBO2 -> CODBO2
	IW6 -> CODG
	SHG -> {CODAW,CODMWR,CODWWII,CODMW2CR}
	IWBO3 -> CODBO3
	IW7 -> CODIW
	IWBO4 -> CODBO4
	IW8 -> {CODMW,CODWZ,CODV}
	IWBOCW -> CODBOCW
	IW9 -> {CODMWII,CODWZ2,CODWZM,CODMWIII,CODWZM,CODBO6}

	idTech4 -> {Doom3,Quake4}
	idTech5 -> {Rage,WolfensteinTNO,WolfensteinTOB}
	idTech6 -> {Doom2016,Wolfenstein2,WolfensteinYB}
	idTech7 -> DoomEternal
	idTech8 -> DoomTheDarkAges

 	idTech5 -> Void
	Void -> {Dishonored2,Deathloop}

	idTech7 -> Motor
	Motor -> TheGreatCircle

    GoldSrc -> Source -> sourcel4d -> sourceas -> sourceportal2 -> sourcecsgo -> sourcedota2 -> Source2
	sourceportal2 -> titanf
	Source -> sourcemp
    {QuakeWorld,Quake2E,QuakeE} -> GoldSrc
	GoldSrc -> {HL,TFC,CSO}
	HL -> {DoD,CS}
	CS -> CSCZ -> CSS -> CSGO -> CS2

	Source -> {HL2,portal,HL2ep1,HL2ep2}
	HL2 -> {HL2DM,HL2ep1}
	HL2ep1 -> HL2ep2
	sourcemp -> {CSS,TF2,DoDS,HL2DM,gmod}
	sourcel4d -> {l4d,l4d2}
	sourceas -> AS
	sourceportal2 -> portal2
	sourcecsgo -> CSGO
	sourcedota2 -> dota2
	l4d -> l4d2
	portal -> portal2

	Source2 -> {dota2,HLA,CS2,Deadlock}

	titanf -> {Titanfall,titanfall2,apex}
	Titanfall -> titanfall2 -> apex
}

I, the copyright holder of this work, release this work into the public domain. This applies worldwide. In some countries this may not be legally possible; if so: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.