to have the images being considered properly in the physically based calculations of the game renderer. While game engines need to have optimized content, and it's recommended to stay within 8bit, future unnecessarily big and you run some scripts to optimize them for your current render needs, making updating the game in the future for fancier screens less of a drag. Normal maps and heightmaps are officially supposed data' working space, but you'll find that most engines will not care much for this. Instead, tell the game engine not to do any conversion on the file when importing. Specular, glossiness, metalness and roughness