This guide is written while the game is in Early Access. The call-in system is mostly fleshed out, and I don't expect there to be big changes to the basic gameplay mechanics. Still, the developers are still adding content and fine-tuning things. I'll do my best to update the guide if and when needed.

Game version at last update of this guide:

Early Access v1.5.0.5 Stable

Note: some images may represent an older state of the game. E.g. the card-colour might be different now for a certain unit type. The guide is still completely valid.
When the game comes out of early access I'll update the images to represent the release version of the game.

The call-in system is quite simple to use: Choose 5 cards, destroy enemy units to get points, then press [1]-[5] to call in support from the card you want to use. Simple enough, right?

That's what I thought too. But there is a little more to it, as you'll find out quickly when it doesn't entirely work the way you thought. Cards that are exhausted somehow when they're not. Pressing the right keys to call in support, but nothing happening. The numbers on cards making no sense. Things like that. Unfortunately the current game manual is still a bit lacking in how it explains things. So here is the comprehensive guide on call-ins.

We'll cover these things in order:

• What does all that stuff on the card mean?
  
• How do those 5 slots work and how do I manage the cards?
  
• How do I actually use them in battle?
  
• Tips
  
• FAQ

Because the the call-in system is quite simple to use; once you get how it works ;-)


Rather skip right to the shortest version? TL;DR is at the bottom.

Let's have a look at a call-in card and see what's on there:
Figure 1: Call-in Card Anatomy

Cards are either an Artillery Salvo or (a) Plane(s). Planes come in 5 varieties: Wildcat, Corsair, Dauntless, Lightning and Warhawk. So there are 6 Card Types in total. Each card has an icon representing its type. Each type has its own colour too, to make it even easier to distinguish them (see table).


*The Lightning and Warhawk can only be obtained as a reward for keeping up a high threat level. More on that later.

Cards can have one of 3 tiers of artillery salvos or aircraft weapons: light (grey text), medium (orange text) and heavy (red text).

Artillery simply has 3 salvo tiers, which speak for themselves:

• light
  
• medium
  
• heavy

Planes can come with any of the following weapons:

• Machine Gun
  
• Machine Gun+
  
• 20mm Cannon
  
• Rocket Pods
  
• 100lb Bombs
  
• 250lb Bombs
  
• 500lb Bombs
  
• 1000lb Bombs
  
• 2000lb Bombs
  
• AP Bombs

The table above shows which plane can come with which weapons. E.g. The Corsair comes with either machine guns (light), 20mm cannons (medium), or rocket pods (heavy)

Note: Planes carrying bombs also have machine guns and will use them!

In the top-left corner of the card is a circle with either an R or a number. The R is shown on cards that are in reserve and not currently in your active slots.
The numbers represent the active slot the card is in (see the Wildcat call-in card below). More on active slots in the section about managing call-ins.

Middle-left is the number that represents how many of the thing on the card you can have in total. So in the image above you get a total of 9 Corsairs with machine guns. This does not mean they come all at once, nor that they can only come one at a time. This number is just the pool from which you draw. More on how this works and what this does in the section about managing call-ins.
When you have used a card, the original number is crossed out, and below it the remaining uses are shown. See image of the Wildcat call-in card below, which has 3 uses remaining.

Figure 2: An active card in slot 3. The card has 3 uses left out of 9

Note: Even though both cards used in the examples happen to give you 9 uses, this number can be anything from 3 up to 9. (3 being the lowest I've seen so far, and 9 the highest.)

The number in top-right corner is the cost of the card in "heat points". Heat points are further explained below in the section about using the cards in an engagement.

Each card has a rank indicated on the middle-right side by one or more ^ symbols. I don't know what the effects of rank are on planes. Considering that higher rank in this context usually means more experienced units, and that higher rank cards cost more, you can safely assume that higher rank cards are better at killing the enemy than lower rank cards.
Artillery rank 2 and 3 should give you an additional salvo to place wherever you want. I.e. you get two for the price of one. (As of v1.5.0.5 this is still not 100% working correctly at all times)

Now that we know what's on the cards. Let's see about managing them and preparing them for use in battle.

Figure 3: The Call-ins screen.

To manage your call-ins, go to the call-ins screen from your map view. (Button in the lower-left hand menu). This can only be done if you are in a friendly port.
You will then see a screen that looks like the one above. Your pool of cards may look different and have a different size. When you start out you only have a few cards available to you. (Also, I happen to have organised my reserve cards by type for my own convenience.)

There are 3 basic parts on your screen:

1. The Reserve Pool on the left
   
2. The 5 Active Slots at the bottom
   
3. On Roll & Rerolling cards on the right

Lets have a closer look.

This is where you store the cards you aren't actively using. That's it. Organise it as you like, or don't that's up to you.

The cards you put here will be available to you in an engagement, and in this order (left to right):

Figure 4: The 5 active call-in slots

Look at the image above: from left to right you have slots 1-5. And the order matters. At the beginning of an engagement you can't use them yet *). But as you gain "heat points" in battle, your cards become available to you starting at slot 1. As you gain more and more points they become available all the way up to 5.

*) Heat points and using call-ins in an engagement are explained in the next main section.

Important: The number on the slot corresponds to how many of the [thing on the card] get called in at once!

If you call something in from slot 2, it will bring in 2 of the [something] at once, and so use up not one, but 2 of the total amount of uses on the card. It will also use up 2x the cost on the top-right corner of the card. For slot 3, it brings in 3, uses up 3, and costs 3x the cost per use, and so on.

Look at slot 5 above. The card has 5 salvos of light artillery available. When I call this in, I spend the whole card all at once, as all 5 salvos are called in at once. After doing this once, the card is exhausted as there are no more uses left.

Now look at what happens if I switch the cards in slot 2 and 5:

Figure 5: The card in slot 5 will not work!

This will not work in slot 5. Calling from slot 5 means you would try to bring in 5 Corsairs at once. But there are only 2 left. In the engagement this slot will say "EXHAUSTED", because it cannot be used.

Important: The number of remaining uses on the card MUST be the same, or higher as the Slot Number you put it in!

Looking at the other slots you can see it's all fine for them. Slot 4 can be used twice to call in 4 Dauntlesses each time. But after that it has but 1 use left and need to go in slot 1 if you still want use out of it. Slot 3 is good too, as there are exactly 3 Wildcats left. Slots 1 and 2 both can be used multiple times before being exhausted.



Figure 6: Rerolling Call-ins and On Roll Cards

Rerolling call-ins is just as simple as clicking that button. You get 6 new cards for the cost of 1500 RP. You do NOT have to have any card in the On Roll section.

Call-in cards with no uses left are automatically removed from your inventory. If you want to dispose of other cards, put them in the On Roll section. Cards can be partially exhausted or brand new. It doesn't matter. Cards will stay here until you do indeed click the 'Reroll Call-ins' button. This means you can leave them there and 'Confirm' and they will still be there when you come back. Only rerolling will replace the cards On Roll.

Note: You do not need to have any card On Roll to get six new cards.

Clicking the 'Confirm' button exits the card management screen, and takes you back to the map. (To reitterate: you won't loose any cards in the On Roll section when you do so.)

So far so good. Now let's actually use them!

First things first: you'll be spending a lot of time in targeting mode, and that's usually when you want to call in support. So check that the following setting is enabled in the game settings:

Important: In the game settings -> controls: ENABLE "Allow Call-ins in Targeting Mode"

Figure 7: Allow Call-ins in Targeting Mode Setting

To use a call-in in an engagement, make sure you are in the right interface: either in the targeting mode [SPACE], or the free camera mode AND your skipper selected. If the cards are all 'down' (Figure 8, top) you're in the wrong interface. Press [SPACE] to go into targeting mode. You'll see the cards are now 'up' (Figure 8, bottom)
Figure 8: Top: cards are down. Press [SPACE] to go into targeting mode first. Bottom: cards are 'up'.


So you are in the right interface, but you cannot use the cards right at the start of the engagement. First you need to gain heat points. When you destroy an enemy unit you get a red pop-up message telling you that you got points. Those are heat points. They accumulate in the yellow bar below the call-in cards.

Figure 9: Heat points

Killing more units in short succession gives you additional points through multipliers. So the hotter the fight gets, the quicker your points you accumulate. And the sooner you can call in additional support. But if there is a lull in the fight or you take it slow, the bar slowly drains!

Important: The heat points bar slowly depletes when you don't keep destroying units. Keep the heat up to keep your points up!

Note: The number on dark-blue above the red pop-ups is supposed to be the total points added from the red pop-ups below it. In the current game version it doesn't work properly yet, and seems off most of the time.

Figure 10: Accumulate heat points to fill the points bar and unlock the call-in slots for use

At the start of the engagement all slots are locked and greyed out. Once you have enough to get the bar fill all of slot 1, it becomes available to you and 'lights up'. If you continue to kill enemy units, the bar fills up further to open up slot 2, then 3, and so on all the way past slot 5. You can now call in support from any of the 'lit up' slots.

When you have a high threat level, you will gain heat points at a small rate without needing to do anything for it. Instead of the bar depleting when you are inactive, your bar starts to fill slowly. See the section on threat level and rewards below.


Now call in support from the slot you want:

• Press [1] to use slot 1
  
• Press [2] to use slot 2 (this will call in 2 of the items, at 2x the cost on the card)
  
• ...
  
• ...
  
• Press [5] to use slot 5 (this will call in 5 of the items, at 5x the cost on the card)

You can use multiple slots at the same time, provided you have enough points.

Once you use a slot, the cost is deducted from your total. So your yellow bar depletes. This may mean that higher slots are no longer available to you until you get more points. The support you just called in will help with that, as it also kills enemy units and so gives you some points back.


When a slot is used, the cards hides or goes 'down' and there is a countdown timer before it can be used again. This is indicated by a white circle above the card:
Figure 11: Slot 1 has been used a while ago and is still on a countdown or reload timer (white semi-circle).


When a card is used up, or doesn't have enough uses left for the slot, it is EXHAUSTED and will stay down. Card that have no uses left at all will be removed automatically, leaving the slot empty. When you're in port, put new cards in the empty slots. EXHAUSTED cards can still be used in a lower slot, so move them there if you wish. Just don't forget to replace them, or you might find yourself in your next engagement with cards you can't use.. (See also the section on managing call-ins and the active slots.)
Figure 12: Slots 2 and 5 are exhausted and cannot be used until replaced in port.


Planes will appear as soon as you call them in, flying in from the edge of the engagement area. Fighter planes will target enemy planes first before strafing/bombing ground targets. Bombers do to, but may not bring enough of a punch to go up against enemy fighters.

When you call in artillery you get a specific targeting interface for it. You can target enemy units about as far as you minimap reaches. Put the reticle over the intended target and [LEFT CLICK] with your mouse.
Figure 13: Artillery targeting interface, while zoomed in with [SHIFT]. A look on the minimap shows the reticle is indeed on target.

Tip: Use the targeting mode [SPACE] and zoom with [SHIFT] to give you a better view. Keep an eye on the minimap to confirm you are on target, and not in front or behind it. It helps if you have your boat on a fixed course for the few seconds you need to put the reticle on target.

Practise in base raids while staying far out and (almost) IDLE. Once you get used to the interface you'll be able to do it while dodging incoming fire too.

Targeting ships may be easier using the minimap, but YMMV. Target slightly in front of them to compensate for the delay before the shells hit.

Important: If the artillery card reload timer runs out before you click on a target, you will LOOSE the call-in. (This may be fixed later, but for the current game version: use it or loose it)

The more often you hit the enemy through raids and engagements, and the bigger your active squadron, the higher your threat level becomes. This is represented by the red exclamation marks in the top-right of your map screen. (See figure 14 below.)
The threat level represents how much the enemy perceives you as a threat. They will deal with that accordingly, but there are rewards for you too.

Figure 14: Threat level and high threat reward cards

When you enter an engagement, your threat level will give you a small passive income in heat points over time. This means the yellow bar below the call-in cards will start to fill by itself, even if you haven't destroyed enemy units yet. The higher your threat level, the faster the points increase.

When you keep up a high threat level, you may be rewarded with additional call-in cards. Those are harder hitting units like the Lightning and Warhawk. Each in-game day you have a small chance to get this reward. The chance is up to 25% when you're at maximum threat level. As seen above, you can get the reward at lower threat levels too, as I was at level 3 at the time.

Do use your call-ins. Even a single Wildcat early-game may make a difference in surviving a wave of Zeros. A well placed light shell salvo can mean a quicker end to a Merchant ship or Coastal Tanker.

Going on a base raid? Put some artillery in slot 1 for a quick end to light and medium gun emplacements.
Expecting waves of enemy planes? Have fighters in your lower slots to give you a breather.
Wanting to down a destroyer? Being medium or heavy shells and some bombs.

It only matters that the card has enough uses left for the slot it's in.

It's easy to forget and end up in your next engagement with the cards that got exhausted in your last one. Wanna know how I know? ;-) So do check your call-ins when in port!

You can simply get a bigger pool by rerolling without discarding anything. So you have more to choose from! (No, that's not an early game thing. Upgrade your boat first: get a main gun!)

Put a salvo of light shells just in front of a bunch of the slow landing craft or amphibious tanks to thin their ranks.

Calling in 1 fighter may not down any Zeros for you, but it will distract some of them long enough for you to take the others on one by one. Your odds of survival just went up.

Out of depth charges or mouse traps? But have some light shells you can use? Put them on the submarine and it will force them to the surface for you to finish off.
(This won't work in submarine-only engagements unless you first killed some, because you need to kill things first before you can use the call-in.)

It makes sense to use the big naval guns on other ships, right? One salvo of heavy shells does a lot of damage to a destroyer. It may just be the edge you need to kill it (quicker). Target slightly in front of it, if it's moving.

• Top left circle: R for reserve, 1-5 for which slot the card is in (= how many get called in at once.)
  
• Middle-left: total number of uses you get. (Or remaining uses if original is crossed out)
  
• Top right: cost per use in heat points.

It doesn't have enough for the slot it is in. Put it in a lower slot.

Those are heat points you get for your action. They also fill up the yellow bar below the call-in cards.

In an engagement press [1]-[5] on your keyboard for slots 1-5. You must have enough heat points to unlock the slot.

In settings -> controls, enable "Allow Call-ins in Targeting Mode"

Currently only the deverlopers know the real numbers, so I don't know. When you're mid-game and have enough fire power on board, those small differences don't really matter in my experience.

In this game, and in my experience, it seems a Corsair has an edge over the Wildcat when they are the same rank.

Yes, both fighters and bombers do. Bombers may not bring enough of a punch to go up against enemy fighters.

In an engagement, killing stuff gives you heat points. (Red pop-ups, and the yellow bar below the call-in cards). More points = more slots unlocked for use. Points reset when leaving the engagement.

Press [1]-[5] on your keyboard to call in a card from slot 1-5. It costs heat points (top right corner of a card.)

Slot 1 calls in 1 of the [items on the card] per call
Slot 2 calls in 2 of the [items on the card] per call, at 2x the points cost
Slot 3 calls in 3 of the [items on the card] per call, at 3x the points cost
...and so on.

If a card has not enough items left for the slot it is EXHAUSTED. Put it in a lower slot, or replace.

P.S. In settings, enable "Allow Call-ins in Targeting Mode"

There you have it: that's call-ins for you. You should be able to use them in combat now. Dismissed, Skipper!

Did this guide help you in any way? Please, give it a thumbs up!

General questions?
Before posting them here, consider asking in the main discussion board for boat crew. I'm just one player who wrote a guide in his free time, but there are many players there who can give you an answer. The developers are often around answering questions too. So you will have an answer much, much quicker!