A minefield has a fixed position in space. Once laid, its position can't be altered. Minefields are circular, the radius is the square root of the mine units laid into the field.
Minefields have an owner which is determined when the minefield is laid and can't be changed afterwards.
There are normal and web mines. The type of minefield is determined by the mission used to lay it, and can't be changed afterwards. Normal mines just damage ships when they go off. Web mines do less damage, but have much higher hit odds. A ship which hits a web mine must stop and burn some fuel. Web mines also drain fuel from ships which just sit in the field.
Only Crystals can lay web mines, but everyone can lay normal mines. To lay a minefield, you need a ship with torpedoes; the torpedoes are converted into mines. Each torpedo converts into a number of mines which equals the square of the torpedo type (i.e. one Gamma Bomb, which is type 4, yields 4*4=16 mine units). Robots are more efficient at this, they get four times as many units. See UnitsPerTorpRate.
New minefields cannot be laid inside an existing minefield of the same type, but you can enlarge your existing minefields to make them overlap.
Players who submit their turn with Winplan or a compatible program will automatically see all their minefields. Others will only see minefields they scan this turn. See MineScanRange, ExtendedSensorSweep.
