A minefield is an area of space that is peppered with warheads that track and launch themselves at passing enemy starships that are unlucky enough to trigger one of them.
A special type of mine, called a web mine, can be created by the Crystals (they can also create normal mines). This type of mine has a few differences from a normal mine. These differences will be discussed in the appropriate locations.
Mines distribute themselves at the rate of one mine every 3.1416 square Light-Years (1.7725 Light-Years x 1.7725 Light-Years). As mines are destroyed or added to a minefield, the mines will automatically redistribute themselves into a circle around the original source of the minefield.
Each minefield will receive a unique Minefield ID. As old minefields are destroyed, their Minefield IDs can be reused.
Minefields are created or expanded when a starship (or a starbase if that campaign feature is available, has been researched and enabled, and Campaign Mode is enabled) with torpedoes chooses the Lay Mines or Lay Web Mines mission. The starship's torpedoes are taken apart by the engineering staff and configured to serve as deep space mines, or web mines, according to the mission set. Torpedoes are divided into one or more smaller units that can cover a greater area of space – the higher tech the torpedo, the more mines it produces. Minefields have a (default) maximum radius of 150 Light-Years (22,500 mines). In Campaign games, this can be reduced to 100 Light-Years (10,000 mines) to free up advantage points for other advantages.
The number of torpedoes converted into mines can be limited with the mdN Friendly Code. The owning player of the created minefield can be changed using the miN Friendly Code. There are some special side effects of Laying Minefields for Other Players.
To determine whether a new minefield is created or an existing minefield is expanded, the Host first needs to find the closest minefield center, where the minefield both is of the same type (normal or web) and has the same owner as the mines being created. If two qualifying minefields have centers precisely the same distance from the minelayer, the minefield with the lowest ID is used. If the vessel laying mines is currently within that minefield, it is expanded. Otherwise a new minefield is created.
To clarify the above, an example can be found here.
|Minefield size for 100 torps||Torps for 100 LY minefield|
|Torpedo||Mines per torp||Most races||Robots||Most races||Robots|
|Mark 1 Photon||1||10 LY||20 LY||10000||2500|
|Proton torp||4||20 LY||40 LY||2500||625|
|Mark 2 Photon||9||30 LY||60 LY||1111||278|
|Gamma Bomb||16||40 LY||80 LY||625||156|
|Mark 3 Photon||25||50 LY||100 LY||400||100|
|Mark 4 Photon||36||60 LY||120 LY 1||278||69|
|Mark 5 Photon||49||70 LY||140 LY 1||204||51|
|Mark 6 Photon||64||80 LY||150 LY 1||156||39|
|Mark 7 Photon||81||90 LY||150 LY 1||123||31|
|Mark 8 Photon||100||100 LY||150 LY 1||100||25|
Note 1: Minefields over 100 Light-Years in diameter can only be created if the Lay Large Minefields advantage has not been disabled.
Starships with beam weapons that are within sweeping range of an enemy minefield can destroy the mines using the Mine Sweep mission. The starship will fire its beam weapons at a wide setting to blanket an area of space with energy in order to knock out the mines in the field. Minefields will shrink in size as the outer mine units move inward so that the level of protection is constant throughout the minefield. The minefield will remain circular and the center of the minefield will not move. Minesweeping of this type can not be performed when the center of the minefield is within an Ion Storm.
If a starship is within range of multiple minefields, all the minefields within range are affected by the Mine Sweep mission.
To sweep a normal minefield, the starship must be no more than 5 Light-Years from the edge of the minefield. To sweep a web minefield, the starship must actually be within the minefield.
The number of mines, in each minefield that's within range, destroyed per turn by a ship doing a mine sweep depends on the type of mine (web mines are swept more slowly than normal mines), number of beam weapons and the beam weapon tech level. Information on the number of mines per turn that a beam can destroy can be found on the Weapon Technical Details page.
In addition, carriers belonging to the Colonies have the ability to use their fighters to sweep normal mines (not web mines), at the rate of 20 mines per fighter per turn. The starship must be within 100 Light-Years of the nearest edge of the minefield to sweep it with fighters.
It should be noted that there are some occasional anomalies related to sweeping web minefields when the sweeping starship is located at the very edge of the minefields. These are replicated but are less evident when sweeping standard minefields at extreme range. In general, sweeping will take place as long as any part of the field in question exists in the same map square as the vessel.
Minefields are swept in parallel with minefield scooping, in ascending Starship ID order.
A starship that has torpedo tubes can scoop up minefields belonging to the starship's owner, converting it to torpedoes. This is done by setting the mission to Mine Sweep, and setting the Friendly Code to MSC. A starship must be inside a minefield to scoop mines from it.
Minefields are scooped in parallel with minefield sweeping, in ascending Starship ID order.
Each turn, just over 5% of the mines in each minefield are destroyed through natural causes. If the minefield intersects a Nebula, the decay rate increases to 15%, due to the high particle count.
Normal minefields and web minefields can overlap. In addition, minefields of races with mutual Diplomacy settings of Safe Passage or higher can overlap. If the Safe Passage is revoked by either race, the minefields will destroy each other.
If a minefield overlaps a hostile minefield, detonations will occur until one or the other is completely eliminated. This check is done in order of minefield ID. Horwasp Protofields are also subject to this mutual destruction.
Web minefields may overlap without limit, and will not destroy either normal minefields or other web minefields.
Each minefield has a Friendly Code. That Friendly Code is set to the Friendly Code of the planet closest to the center of the minefield and owned by the minefield's owner. The minefield Friendly Code is initialized shortly after the minefield is initially created, and is reset once per turn.
Any starship that matches a minefield's Friendly Code may pass through the minefield without risking damage. In addition, if any planet belonging to the owner of the minefield has a Friendly Code of MFx (Universal Minefield Friendly Code), that Friendly Code will provide safe passage through all the minefields belonging to that player. If there are multiple Universal Minefield Friendly Codes set, only the one on the planet with the highest ID is used.
Minefields for a race that has no planets will have the Friendly Code of the last planet controlled by that race if they were created prior to the loss of that planet, and 000 if they were created after the the last planet was lost.
When an enemy starship is inside a web minefield owned by a Crystal player, after sweeping, the starship will be required to have its shields up, consuming 25 KT of Neutronium for each such minefield. No report will be generated for web drain. If, after web drain occurs, an enemy starship in a Crystal web minefield has no fuel, any mission other than Beam up Fuel will be reset to Explore .
An enemy starship has a 1% chance of hitting a normal mine for every Light-Year traveled. It is very likely that a starship that travels through 150 Light-Years of minefield will hit a mine, but there is still a slim chance that the starship won't. A cloaked starship has a 0.5% chance of hitting a mine for every Light-Year traveled.
The amount of damage done to a starship depends on the mass of the starship's hull. One mine hit will deliver 100% damage to a starship with 100 KT hull mass (Hull mass, in this case, does not include the mass of components, fuel, or cargo). A starship with a larger mass will take proportionally less damage, while a starship with less hull mass will be completely destroyed.
Damage % = 10000 / (Hull Mass + 1)
Most battleships and heavy carriers have hull masses over 500 KT, so they can take 6 or more mine hits before being destroyed — unlikely in a single turn, but possible. A starship that is under tow (moving by being towed) cannot be hit by a mine.
A starship hitting a mine can be slowed by 10 Light-Years for every mine hit the starship takes. Starships below hull tech 7 that hit a mine will be slowed by 10 Light-Years if they have more than 10 Light-Years to travel when the mine hit occurs.
It is possible to hit multiple mines when passing through a minefield. Additionally, when traveling within overlapping minefields, or on any course where both the X and Y coordinates change, it is possible to hit more than one mine in the same location.
Finally, when traveling in any non-Cardinal direction (any direction other than directly North, East, South or West), it is possible to hit two mines in a single minefield. Overlapping minefields can compound this.
An enemy starship, whether or not it's cloaked, has a 5% chance of hitting a web mine for every Light-Year traveled. It is very likely that a starship that tries to travel through 30 Light-Years of minefield will hit a mine, but there is still a slim chance that the starship won't.
The amount of damage done to a starship depends on the mass of the starship's hull. One web mine hit will deliver 10% damage to a starship with 100 KT hull mass (Hull Mass, in this case, does not include the mass of components, fuel, or cargo). A starship with a larger mass will take proportionally less damage, while a starship with less hull mass will take more damage.
Damage % = 1000 / (Hull Mass + 1)
A starship that is under tow (moving by being towed) cannot be hit by a web mine.
A starship hitting a web mine is instantly stopped, and it's speed is set to Warp-0. It will have consumed the amount of Neutronium for the movement scheduled in the turn, even though it only made a partial trip In addition, Neutronium is destroyed. The amount of Neutronium destroyed is the greater of 50 KT or 1/6 of the Neutronium on-board at the beginning of the turn. If, after a web mine impact occurs, an enemy starship has no fuel, any mission other than Beam up Fuel will be reset to Explore .
When traveling within overlapping minefields, or on any course where both the X and Y coordinates change, it is possible to hit more than one mine in the same location.
If a starship is moving faster than Warp-1, and hits a web mine in a warp well , the starship will end the turn orbiting the planet.
Starships set to Mine Sweep will detect any minefields when within 200 Light-Years of the nearest edge. They will generate a report on all minefields within this detection range. Enemy minefields that have Friendly Codes that match your starship's Friendly Code will generate reports that safe passage has been granted.
If the center of a foreign minefield is within an Ion Storm, changes can not be reliably scanned.
There is a soft limit of 500 minefields. After 500 minefields exist, laying a new minefield may cause older minefields to be removed. To be eligible for removal, the minefield must have fewer than 1000 mines and there must be no enemy starships within 200 Light-Years of the minefield. The smallest minefields will be removed first. The removal will be done at the beginning of the turn after the minefield requiring the removal was laid, or the turn after the last enemy ship is no longer within 200 Light-Years.
The miN Friendly Code can be used to lay mines in the ID of another player. There are several special concerns when using this Friendly Code:
When playing in a Campaign game, there are several starbase advantages that can be researched and enabled. Some of those starbase advantages have an impact on minefields, specifically, the Starbase Mine Laying , Starbase Mine Sweeping and Starbase Fighter Sweeping advantages.
In all three of the above, the starship version of the advantage occurs immediately prior to the starbase version. Additionally, both versions happen in ID order.