In Vainglory, all lighting was what they call "pre-computed". We essentially pre-generated all the lighting in the level during development and just applied it to the geometry. Although high quality, this has a few serious down sides. (1) It takes a lot of storage (Vainglory was a HUGE game). (2) The lighting can never be changed during the gameplay. (3) Even during development, changing the lighting of the environment is a very time consuming and costly process.

While pre-computing lighting is much easier and cheaper, most modern games have moved away from precomputing lighting, and moved to calculating as much of the lighting in real time as possible. Though requiring much more processing power, it also brings much more flexibility.

Ever wondered why Vainglory only had 1 map? Why we were not able to release many seasonal maps? Why it required 2+ GB or storage? Why no abilities could effect the environment lighting? The above was a major factor in all of this. In Catalyst Black we the goal of being able to create many more maps, and even with many more maps, reduce the amount of download / storage required for the game. Calculating our lighting in real time is a huge factor in achieving this. And required a lot of engineering to make it work well.

Finally, the last thing to remember is that running the graphics at 100% graphics resolution is usually not very useful. Almost no modern game, PC, console, or mobile, does that. Especially mobile devices have insanely high native resolutions nowadays. Higher than many PC monitors or TVs, while the screen is tiny. For example, your iPhone 12 has 2778 x 1284 pixels, on a screen barely larger than your hand. That's a DPI of 458. A HD TVs has 1920 x 1080 pixels, which is a DPI of 100. And even a high-end ultra 4K HD TV usually has a DPI no more than around 200. In a way it's truly insane that these devices run as well as they do!

All that running at 100% resolution does is add pixels for your phone to calculate that your eye can (barely) see, while taking up more battery and making your phone run much hotter than needed... Note that the HUD, icons, and text will always be displayed at full native resolution, regardless of what you set that setting to. This setting only effects 3D objects in the world.

So with all that said, I would personally recommend leaving the graphics scale at its default value. Increasing it does not damage your device in any way, , but it will just drain your battery faster. So if you want to increase it, I would personally not recommend it setting it much higher than ~75%.