Hi, can this somehow be used to upgrade graphics, add post processing etc
Of course - if it's a game, you could write your own DLL to hook into the render process and handle post-effects depending on which engine and graphics API the game uses. But then again, that's exactly what tools like ReShade already do effortlessly. Otherwise, you'd have to spend a ton of time reverse-engineering the game to understand how its rendering pipeline works. But in simple terms, yes, it's totally possible: you can write a custom DLL that adds post-effects to the game.