Elemental makes use of a brand new 3D engine developed specifically for PC strategy games. Its multithreaded design along with dynamic LOD (level of detail) allows for it to look great on a wide range of hardware.
To see and understand why Elemental can look good on low end hardware and yet benefit further from higher end hardware see for yourself how the dynamic LOD works:
Look very very closely here. This isn’t one 3D object. This is dozens of 3D objects. The engine determines how powerful your hardware is and based on that can choose to display objects based on that.
As more objects come into view, certain “less important” objects start to fade away:

Did something change?
Look closely. Did something change?
How about now?
As a result of the object-based system that Kumquat provides, the graphics look identical at a casual glance and yet, the polygon count is dramatically less in the third image.
And users with very low end hardware can simply play using the sprite based output (cloth map mode):
Because Kumquat is a PC-only graphics engine, it can make a different set of trade offs than the traditional cross-platform engine. Namely, it can assume players have a considerable amount of memory (1 gigabyte is the minimum total system memory to play a Kumquat based game – very little on a PC but twice what a current generation console has). Thus, a given game object can be made up of many sub-objects (which use more memory) but can be dynamically turned on or off based on 3D hardware instead of having to load up lower-quality 3D models.