The Shimmering Frontier
Overview
The Shimmering Frontier is a late-game biome made up of crystal-themed terrain and one of the outer regions of the world. It is notable for its rare dungeons, unique fishing results from shimmering water, and the alien technology found within some of its scenes. Before release, the biome was referred to by the developers as the “crystal biome.”
One of the most distinctive structures found here is the alien tech lab, a small dungeon that generates rarely in the Shimmering Frontier. Some of these labs contain a challenge arena: a circular room with a glowing terminal in the center and Materializers around the edges. Interacting with the terminal starts a wave-based event, causing enemies to spawn from the Materializers while a green ring marks the active area. Staying inside the ring fills the terminal gauge; leaving it causes the ring to turn red and the gauge to drain. When the gauge is filled, all remaining enemies are removed and a reward chest appears in the middle of the room. If the gauge is fully depleted, the terminal deactivates and the enemies are cleared until the challenge is attempted again.
The arena has a few important quirks. All objects inside it are indestructible until the challenge is completed, and defeating every enemy is not required to finish the event. The reward chest contains 2–3 upgrade gems depending on the biome the arena is in, 5 random loot rolls, and the Nuclear Battery, though the battery only has a 20% chance to appear if the 
Shimmering water in the Shimmering Frontier can be fished in any biome, and doing so yields the special shimmering-water catch table. 
- The biome was previously represented in development by blobs of Obsidian Blocks, likely to hint at future content and to keep long-time players from needing to travel too far to find it.
- These placeholder blobs grew larger and more frequent the farther out the player traveled, and could merge with other sub-biomes and scenes in unusual shapes.