Large scale environment project done in Unreal Engine 5, and an additional smaller environment done in Unity for VRChat.
The Unreal project involved a lot of research since I wanted to make everything from scratch, including the landscape and skybox materials. I checked out Gaea and World Machine for terrain creation (in the end I chose to use Gaea). I also learned about Speedtree, Quixel Megascans, and more about Unreal materials/workflow.
Unity version involved a lot of optimization so it can run well in VRChat. While each foliage asset in Unreal had its own material with a 2048 texture, I put everything together into one material with everything atlas'd into one 1024 texture. I also brought over the LOD1 meshes to use as the LOD0 instead for lower polycount. The terrain is a lot smaller and I added heavy fog so distant foliage can be culled unnoticeably.
Quixel Megascans: Cliff and rock models, textures for foliage
Photoshop: Editing quixel textures
Blender: For making any tweaks on the models
Spacescape: Nebula and star textures for the skybox
Flowmap Painter: For creating the flowmap for the aura in the skybox
Unreal Engine 5: Engine for the large scale scene. Movie Render Queue was used for rendering images.
Unity: Engine for the small scale scene.