idtech2 (Quake 1 Engine) - 1996

idtech2 is a game engine developed by id Software, first used in the 1996 first-person shooter game Quake.
idtech1
↓
idtech2 (Quake 1 Engine)
CustomTF - 1996
Mega Team Fortress - 1996
Quake - 1996
QuakeWorld Team Fortress - 1996
Quake 2 - 1997
Attackers Go Red - 2000
Soldier of Fortune - 2000
FortressOne - 2019
↓
idtech3 (Quake 3 Engine) (1998) GoldSrc (Half-Life Engine) (1998)