QuakeSpasm

The Quake engine (Also known as id Tech 2) is the game engine developed by id Software to power their 1996 video game Quake. It featured true 3D real-time rendering. Since 2012, it has been licensed under the terms of GNU General Public License v2.0 or later.

After release, the Quake engine immediately forked. Much of the engine remained in Quake II and Quake III Arena. The Quake engine, like the Doom engine, used binary space partitioning (BSP) to optimise the world rendering. The Quake engine also used Gouraud shading for moving objects, and a static lightmap for non-moving objects.

Historically, the Quake engine has been treated as a separate engine from its successor, the Quake II engine. Although the codebases for Quake and Quake II were separate GPL releases.[1][2], both engines are now considered variants of id Tech 2.[citation needed]