What Makes Housing Corrupted in Terraria?
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In the blocky, vibrant world of Terraria, providing suitable homes for your NPCs is crucial for progression and unlocking various services. However, your meticulously crafted dwellings can sometimes fall victim to the insidious spread of Corruption or Crimson, rendering them uninhabitable. So, what exactly makes housing corrupted in Terraria?
Essentially, a house is considered corrupted when the evil biome presence is too high within a certain radius of the housing. If the “evil score”, calculated based on the amount of Corrupted or Crimson blocks nearby, exceeds a certain threshold, the game flags the house as invalid, and your NPCs will refuse to move in or might even abandon their current residence. The specific thresholds are important to note:
- Evil Score ≥ 50: The housing is considered invalid, and the message “This housing is corrupted” will be displayed.
- Evil Score ≥ 300: The message changes to “This is not valid housing,” indicating a much more severe level of corruption.
This “evil score” is determined by the density of Corrupted or Crimson blocks (Ebonstone, Crimstone, Corrupt/Crimson grass, Corrupt/Crimson sand, Corrupt/Crimson trees, etc.) within a 45-block radius of the house. If there are enough of these blocks to push the evil score above the threshold, your perfectly good-looking house becomes a no-go zone for NPCs. This mechanic forces players to be mindful of biome placement and active in preventing the spread of these biomes throughout their world. Managing biome spread isn’t just about aesthetics; it’s a core part of the gameplay loop that directly impacts your ability to progress and interact with the game’s many features.
Understanding the Corruption and Crimson
The Corruption and Crimson are two evil biomes that pose a significant threat to the Terraria world. They slowly spread, converting other biomes into their respective forms. The Corruption is characterized by dark, ominous landscapes, Ebonstone blocks, and unique enemies. The Crimson, on the other hand, is a blood-red, fleshy biome with Crimstone blocks and its own set of challenging creatures.
Both biomes spread by converting certain blocks, like Stone and Sand, into their respective evil versions. They can also convert grass into Corrupt/Crimson grass, allowing them to spread across the surface. This spread becomes much faster after defeating the Wall of Flesh and entering Hardmode. After entering hardmode, these biomes have the potential to spread much faster, especially through the use of thorns underground.
Safeguarding Your Housing
Preventing housing corruption is vital for maintaining a functional base and ensuring your NPCs stay happy and productive. Here are some key strategies:
- Early Containment: As soon as you identify Corruption or Crimson spreading, take steps to contain it. Dig wide trenches (at least 3 blocks wide) around the biome to create barriers. These trenches should extend to the Underworld to be fully effective.
- Non-Corruptible Building Materials: Use blocks that are immune to Corruption and Crimson, such as Gray Brick. These blocks can form the foundations of your structures and act as buffers against the spread.
- Sunflowers: Place Sunflowers near your housing. Each Sunflower reduces the Corruption rating of the area by 5 tiles. While not a foolproof solution, they can help mitigate minor corruption.
- Clentaminator: The Clentaminator is a powerful tool purchased from the Steampunker NPC (after defeating a mechanical boss). It uses various colored Solutions as ammo to convert blocks. Using Green Solution (which converts blocks back to their original form) or Blue Solution (Hallow) near your housing can eradicate nearby corruption. The Hallow biome is not considered evil and doesn’t affect housing validity.
- Strategic Hallow Placement: The Hallow biome can be used to counteract Corruption and Crimson. The Hallow doesn’t corrupt housing.
Frequently Asked Questions (FAQs)
1. What are the minimum housing requirements in Terraria?
Housing must be at least 10 tiles wide (interior) and 4 tiles tall (interior). It needs walls on all sides, a door, a table or workbench, and a chair. The structural walls and ceiling must be made of non-corrupted materials. The internal space must also have player-made background walls, which can be crafted.
The optimal room will have a living space of at least 30 blocks (60 including walls, floor, and ceiling) to accommodate NPC movement and functionality.
2. How can I check if a house is valid?
Open the housing menu (accessed via the inventory screen), click the question mark icon, and then click on the house in question. The game will tell you if the house is suitable and, if not, will provide a reason. This is a good way to determine if the evil biome is too close.
3. Why is my NPC house not valid even though it seems structurally sound?
There are a few reasons: The house might already be occupied, it might be too close to an evil biome, or there might not be a suitable place for the NPC to stand inside at night.
4. Can NPCs go through platforms?
NPCs will always climb up platforms but cannot go down through them. Flying enemies can fly through platforms, while other enemies might ignore them entirely.
5. Does breaking demon altars spread corruption?
Yes. Each time you destroy a demon altar, there is a 66.67% chance that a random Stone Block in the Cavern layer will be converted to Ebonstone/Crimstone or Pearlstone, facilitating the spread of Corruption/Crimson or Hallow.
6. Do sunflowers completely stop corruption?
Sunflowers prevent the two tiles directly underneath them from being converted. They also decrease an area’s total Corruption rating by 5 tiles. However, they don’t provide complete protection, especially in heavily corrupted areas.
7. Can gray bricks be corrupted?
No, Gray Brick is resistant to the spread of Corruption, Crimson, and Hallow, making it a useful building material.
8. Can NPCs live in Crimson biomes?
No, NPCs will not live in housing located near Corruption or Crimson. If these biomes spread too close to an occupied house, the NPC may move out.
9. How does Corruption spread in Terraria?
Corruption spreads through Sand and Stone and slowly converts Mud to Dirt (after defeating the Wall of Flesh). It requires 200 Ebonstone blocks to create an artificial Corruption biome.
10. How many houses do I need in Terraria?
You’ll eventually need 26 houses to accommodate all NPCs, including Santa Claus (who only appears during the Christmas season).
11. Can NPCs live in the Hallow?
Yes, unlike Corruption/Crimson, NPCs can live in the Hallow without issue.
12. Can Hallow overtake corruption?
Yes, the Hallow is an anti-Corruption biome and can be spread using Hallowed Seeds, Holy Water, or the Clentaminator.
13. Which is better, Corruption or Crimson?
The Corruption is easier in pre-Hardmode. Crimson has very annoying enemies to deal with early on but ends up with much stronger benefits in Hardmode, such as Vampire Knives and Ichor.
14. How many altars should I destroy?
Destroying too many altars can lead to excessive spread of corruption. Six is often considered the optimal number for balancing ore generation and corruption risk. Every 3 altars destroyed reduces the ore generation of subsequent altar smashes, but still spawns infection.
15. Can Crimson infect Corruption?
Although Corruption might replace Crimson at world generation, it does not prevent Crimson from being artificially created in a Corruption world, and vice versa. Spreading remains normal.
Ultimately, keeping your housing free from corruption requires vigilance, planning, and proactive biome management. By understanding how the Corruption and Crimson spread and utilizing the tools and strategies available, you can create safe and welcoming environments for your NPCs, ensuring a thriving and functional Terraria world. For more insights into game mechanics and learning through games, be sure to check out the Games Learning Society at GamesLearningSociety.org.