So what’s the big deal here? Well, Nvidia hasn’t changed anything about Quake II except for the way the lighting works. The company took the open-source code for the game and compiled it with its RTX technologies. That includes ray tracing for global illumination, shadows, reflections, and ambient occlusion. All of that works together to create a really excellent demonstration of what ray tracing can do for game visuals.
While standard Quake II uses flat, prebaked lighting, RTX brings the world to life. Light bounces off of your weapons and walls. If a room has four distinct light sources, your character creates four distinct shadows on the wall.
RTX even slows down Quake II
Quake II RTX looks impressive, but RTX is extremely demanding even in this ancient classic.
I was getting about 70-to-80 frames per second at 1080p during standard gameplay with everything turned on and set to high on an RTX 2080 Ti. In the OpenGL version of Quake II without RTX lighting, I can get a framerate in the hundreds.
And the reason for that is really the global illumination. Every light in the game world is bouncing off of multiple surfaces before it reaches the in-game camera, and the GPU needs to calculate all of that for every frame. So it doesn’t matter if you are playing a low-polygon shooter from the 1990s. That doesn’t really do anything to make it easier to process the behavior of light for the video card.