Defence System

There is a "Blood Moon Raid" system in VISM, which comes once every 14 days, with a large number of mobs attacking the base that player has build up. The defense system exists to protect village which taking the time and effort to develop from the mobs that come in large numbers.
== Defence System ==
Defense system is the general term for installed defense items that you can craft with the crafted furniture Armillary Sphere. After the defense system is installed, it must charge fuel(ammo) in advance. Most of the fuel can also by crafted with Armillary Sphere.
The installed defense system automatically attacks the target when an enemy enters its reaction area. It consumes fuel in operation. Because of its auto-attack feature, it is mainly used for base defense in the game.
Durability of the defense systems can be reduced by attacks from mobs and other causes. It can be repaired by having repair materials in the inventory and interacting with it.
The defense system reacts only to enemies, but depending on the game difficulty setting, players and villagers may be hit by bullets from defense systems.
The installation of defense systems is limited to the ground surface, but there is no limit to the number of installations.
== Types and Functions ==
=== Spike Tile ===
Spike Tile is an effective defense system for an area of one map tile. When an enemy comes on a spike tile, spikes automatically pop out and damage the target. It's range is small, but the damage occurs quickly. So it generally works effectively against mobs that appear during Blood Moon. Spike tiles do not require charging and crafting is made from common materials, so there is no difficulty in gathering materials later in the game. However, it is difficult to repair during a Blood Moon because of it's direct attack defense system.
It does not hit a floating mobs as it looks.Flame StatueFlame Statue is oil-fueled defense system which do damage and spread fire effects to the mobs in front of them. This is effective against mobs that are crowded together, such as by a wall, because the fire will spread to the mobs around them. 
Auto Ballista
This is a defense system that targets an area in a forward cone and automatically shoots a bow. Comparing this with the two in the previous section, the automatic crossbow has a longer interval but also does more damage. Arrow shot pierces mobs, but does not pierce any other objects in its path.
Auto Canon
Auto Canon also targets an area in the forward cone same as Auto Ballista. The two differ in that Auto Canon does more damage and generates area damage at the point of impact.In addition, the firing interval is longer, and the time between firing and impact is longer, making it difficult to target fast-moving mobs.
The main advantage of Auto Canon is that bullets fired from the cannon fly in a parabolic path, allowing the cannon to attack across barricade walls. Ammo can be safely reloaded while in a battle by placing the cannon inside barricade walls.
Acid Crowder
Acid Crowder is a defense system that generates a poison effect in a circle area centered on itself. Poison damage seems low at 18 damage per 20 seconds, but the poison area crosses walls, so it is possible to install it with surrounding walls it for protection. This also makes it easy to deal with multiple mobs because the poison effect continues for several seconds.
Thunder Striker
Thunder Striker has a circle area centered on itself as its alert range, just as Acid Crowder does. When the enemy enters the area, it generates lightning damage there. The attack area is narrow, but it functions like a cannon, so it hits multiple enemies. It works well against a single enemy. On the other hand, it is not good against multiple enemies spread out.
== Others ==
=== Barricade walls and gates ===
See the Building and Tile article for more durable barriers than regular walls and gates that allow for set rules of passage.
=== Guardpost(Village Facility) ===
Guard post is facilitiy where armed villagers wait and patrol. Once villagers are assigned to Guardpost, armed villagers patrol a large area centered on that post to eliminate the enemy. They can also have them charge defense systems in the area and repair barricade walls.
*See the Village Facility article for building requirements and detailed structure.
This feature has not been implemented yet, and the implementation of the feature is included in the planned update of the alpha version.