QUICK EXPLANATION
ReShade is a generic post-processing injector for games and video software developed by crosire. This means that ReShade is able to hook itself into all kinds of 2D and 3D video software by intercepting the communication of the software with the video card, and is capable of adding custom graphical effects on top of what the target software displays on its own.
ReShade acts as the base layer of communication with the game, and as such produces no visual changes itself, it functions merely as an interface for users to easily add graphical effects. This may sound simple, but ReShade can handle all the different ways a game can talk to the video card, it features its own programming language for the effects and is even backed by NVIDIA, as the ReShade shader compiler is integrated into the NVIDIA driver, allowing many effects developed for ReShade to be used via NVIDIA Ansel / FreeStyle.
What changes the game’s graphics are shaders, pieces of code written for video cards to produce all kinds of visual effects. Think of them as math-dense scripts that are responsible for pretty much everything you can see in a video game. Reflections, shadows, translucent skin, glowing light sources, fog, clouds, if a game has these effects, a shader creates them. With ReShade, you can load, combine and customize shaders written in ReShade FX to every game you want, modifying, extending and improving the default graphics.
A small community of shader developers has been creating a large collection of different shaders for you to use, and presets for them exist for literally thousands of games. A ReShade preset is basically a very simple list of which shaders to enable, and values for their parameters. So with a preset defining which shaders to use, the shaders creating the visual effects and ReShade doing the heavy lifting of implementing all of this into the game, transforming any game is really simple. Due to its generic nature, ReShade is compatible to new games as they come out, so you can transport your work on whatever game you want!
This makes ReShade an invaluable tool for modding games, as no matter how resistant the game is to native modding, i.e. swapping 3D models, textures, scripts and other assets, there’s always ReShade.
