These are some Tribes-inspired levels designed with the help of procedural terrain generation programs World Machine, Geoglyph and World Creator. The castle above I commissioned and modified. The rest of the structures I modeled in Maya or Sketchup. The terrain textures I purchased from CGTextures and Gametextures and the skies are from UDK.
I had trouble finding trees with the right low poly stylized look I was going for, so I purchased the only one I liked, smoothed it out a bit and then broke it into pieces and reassembled them in Blender to create a variety of trees with the same style.
I created all of the environment materials on this page in Unreal. They’re not as good as what an artist would come up with but they look nice enough as a starting point. For the level above I purchased a clump of three palm trees, separated them and cleaned up their overlapping leaves.