# What are mechanics to getting a reaction shot in Xenonauts?

Sometimes, Aliens run through my sights, but I don't get a reaction shot. Sometimes that even happens when the Alien ends up stopping in my field of vision. What's going on?

## Initiative System

Although some forum posts incorrectly claim that reaction shots are chance based, the Xenonauts Quickstart Guide explains that reaction fire in Xenonauts works on a deterministic initiative based system. The formula to calculate a unit's initiative is:

``````initiative = Reflexes x Weapon Reaction Modifier x %TU_left
``````

Notably the same rules apply for the Aliens and your soldiers in their turn and yours. This means that soldiers carrying pistols and shotguns will also trigger fewer reaction shots!

## Weapon Reaction Modifiers

• Pistols & Shotguns: 1.5
• Rifles: 1.0
• Sniper & MG: 0.5

The same modifiers apply to the later replacements and most Alien weapons. The Alien Sniper breaks the pattern: its reaction modifier is 1.0.

## Example

PFC. Kuznetsova has 27 of 45 TU left and is using a rifle. Her Reflexes stat is 53. Her resulting initiative score is `53 x 1.0 x 0.6 = 31.8`.
An Andron Guard (TU: 45, RFL: 60) steps into her field of view. The Andron is carrying an Alien Plasma Rifle and has taken three steps already. The Andron has 36 TU left and therefore its initiative is `60 x 1.0 x 36 / 45 = 46.7`. The Andron turns 45° to face Kuznetsova (1 TU) and takes a snap shot (13 TU), reducing it to 22 TU. The Andron now has an initiative of `60 x 1.0 x 22 / 45 = 29.3` which is below Kuznetsova's 31.8. Kuznetsova gets a reaction shot, before the Andron spends its remaining TU.

Had PFC. Kuznetsova been equipped with a shotgun or pistol, her initiative would have been `53 x 1.5 x 0.6 = 47.7` and she would have gotten a reaction shot when the Andron walked into her field of vision. Vice versa, had the Andron stopped performing actions after stepping into sight, Kuznetsova would not have gotten a reaction shot at all.

## Some Tactical Implications

Understanding the above mechanic provides some tactical implications.

• If multiple soldiers are in the field of view of an enemy, the enemy's reaction fire can be delayed or avoided by taking one shot at a time with each soldier before exhausting any one soldier's time units.
• When coming upon a new enemy, reaction shots can be avoided by stopping immediately, and bringing another soldier with higher initiative in to take a shot or bringing a shield up front.
• By bringing a shield up front and exhausting the shield's TU completely (e.g. by taking shots even though the success chance is tiny or crouching and standing up), all reaction shots can be exhausted and other soldiers can move in with impunity.
• Operating outside of an enemy's line of sight will never trigger reaction shots. Sneak up from behind!

As Wipqozn explains:

Reflexes (1): A progress point is gained when a soldier performs a Reaction Fire test

And the Quickstart Guide states:

REACTION FIRE:
• If a unit has enough unspent TU to fire their weapon, they may take a Reaction Fire check when a hostile unit performs an action in the line of sight during the enemy turn

I therefore deduce that you gain a point in reflexes (since it takes one progress point to level) once per mission, whenever an enemy performs an action in their field of view while the soldier has enough TUs left to take a shot, even if the soldier does not end up taking a shot.

• Whose action count toward the initiative check? I mean: soldier enters alien's field of view (spotting the alien; TU high enough no reaction). Another soldier, far, far away, with the alien out of sight range (and vice versa?) opens automatic fire at the alien, to TU depletion. Will the alien react?
– SF.
Commented Jan 28, 2020 at 10:24
• Units will only react to actions within their line of sight. I've updated my answer to clarify this point Commented Jan 28, 2020 at 17:12