opportunity fire?

[doctor_atomic]

While playing a single player game I noticed that some of my units would automatically fire when an enemy came into range, but I don't understand the rules behind this. Is this part of moving in "hunter" mode?

thanks

[Richcat]

This might help from Manual additionsviewtopic.php?f=87&t=19482

Reaction Fire

* Units that are hidden will not shoot and reveal their position unless they have a significant chance to hurt the enemy, or when they feel its time to shoot or die.
* Units that are hunting are harder to detect and your men may not notice them.
* Units always get a bonus shot in the opponents turn for opportunity fire. If they did not shoot in their turn they also get their base 2 shots. If they are elite they can get an additional bonus shot.
* Units that are visible will fire all but their last shot at anything they detect. Their last shot will be saved for something they think they can hurt, or when they feel its time to shoot or die.
* Units that are close to be suppressed will fire their last shot as there is a good chance that waiting for the enemy to shoot will mean you're suppressed and never get the chance to fire back.
* The criteria for damaging the enemy reduces as they get closer. E.g. at long range you might need a 25% chance to use your last shot or fire from cover. When adjacent you always shoot, even with a 0% chance to hurt them.