Using Blender (2.90) I created a node group that can add procedural snow to any imported terrain. The node group can be applied with only a few adjustments required to each new environment. This can be controlled on X,Y and Z axis, this is particularly important for the Z axis in order to keep the snow off of the sea.
Armory3d is a completely open source game engine that is fully integrated into Blender. Below is my first attempt at stitching a terrain mesh, layered with satellite/flown imagery, making use of the excellent BlenderGIS plugin. You can then simply export the project to an HTML5 application which can run on any browser.
See below a second attempt with some slightly higher resolution sat data, with some improvements to control methods (detailed below). Use WASD keys & left mouse button for controlling camera, sun direction and shadows can also be adjusted with keys – T,Y,G,H,B,N: