Just the very basics, like:
- 2 building types
- 2 unit types (with minimal or 0 animations needed. Units like floating heads and such are good for this)
- 2-3 ground textures that can be mixed & matched together.
- Trees and other doodads (applicable to other games too).
Plus the buildings and units should have team colors. @methusalah tells me “it’s only a matter of making a submesh”. You can probably poke him for slightly more specific details.
Another cool low-poly project worth looking at is lowpolyfactory.com. Blender-based asset generator for trees, rocks etc.