This is a paid asset, but now you can download Top-Down Cave Tileset Free.
Detail this asset from Unity Store: Original Link
Top-Down Cave Tileset v1
Note: This asset works in Unity 5.
This is the definitive environment set that has everything you need to easily create mind blowing subterranean caves that will make your gamedev projects rock!
Here is just a taste of what you can make with this tileset:
Youtube Video
Webplayer Demo – Cave – Vegetation
Webplayer Demo – Cave – Volcanic
Webplayer Demo – Cave – Ore
Webplayer Demo – Cave – Desert
What you get in this pack:
-A complete set of modular, tile-based, lowpoly cave models, organized in prefabs with attached collider geometries, all mapped to a single texture page for draw call efficiency.
-Multiple cave styles using swappable textures which allow you to easily reuse existing layouts.
-Example scenes showing you how to best arrange, combine, and light the different elements for maximum visual appeal.
-Additional FX prefabs to help bring your cave environments to life.
Also, check out the forum thread for more information.
Developer Support Email: [email protected]