1. The graphical settings in standalone games affects only Shaders. This can be enought, but for most developers, this means they have to choose between quality or performance, because settings like Lightrays or Vegetation eats alot of performance. The best way, how to fix this will be making something like this.
Ofcourse, for GameGuru the settings will be different. There will be those options: Water and Reflections, Shadows, Bloom, Lightrays, Vegetation, Terrain Shader, Entity Shader, Grass Shader, Distance Trasition, Transition Range, Terrain LOD Near, Terrain LOD Midrange, Terrain LOD Far, Terrain Size, Vegetation Quantity, Camera Distance and LOD Scale/Entity distance ratio (see 2.). You will be able tweak the presets, like is shown on the picture before. Those presets will be shown in standalone game: Lowest, Low, Medium, High, Highest and they will affect those options.
2. GameGuru have object distant fading. But it can´t be controled by user, it´s fixed. So there will be slider, that can change that. With ratio 1, the view distance for objects will be at GameGuru default, with ratio 0,5, the draw distance will be halved, with 2, draw distance will be doubled.