hello again, I am once again creating a guide for the prequal to the CE games.

In this guide I will not be telling you the gameplay basics like how to control units or use the keybindings.

I will be telling you information about events, leveling, some stage guides and achievements.

I HIGHLY recommend playing a few times first before using this guide, it spoils a lot of the maps.
Another reason why I recommend playing a few times on your own is so you unlock some of the achievements.
A few you will want are ones that unlock 3 starting soldiers, 5 max soldiers, any and all bonus starting goodies, at least lvl 3 in every ammo type as well as in meds and food. start with soldier armor is another good one. getting units started at level three is nice as well if you got nothing better. like decoy which reduces noise.

Similar to the first CE game, you will be going through a series of events before you do a stage, unlike the previous two games however, there is not map layout to pick and chose from. your path is always going to be rng choices of ABC.

These paths are fairly global and are usually accessable, unless you do not meet the requirements in order to do them in some shape or form. For example the make camp choice requires at least 1 morale be gone in order for it to come up. I will post an entire list of events later. For now they can be summed up as the good, the bad, and the loot.

important tip: currently only the engineer can both increase loot speed AND increase loot amount.

guide version
V 1.00 ; 02, 07, 2025
V 1.01 same day - did some edits, started on D4 section
v 1.02 ; 02, 08, 2025- finished D4 and did most of D3 maps
v 1.03 same day - finally beat the game. got a bit for all the remaining maps
v 1.04 02, 11, 2025- started working on outside battle events and unit types levels and gear.
v 1.05: added some suggested unit builds


TOC:

1: outside battle events
1.1: camp
1.2: encounter (not done)
1.3: explore (not done
2: maps
2.1: DC5
2.2: DC4
2.2.5: DC4.5
2.3: DC3 partly done
2.4: DC2- not there yet
2.5: DC1
3: units- not done
3.a: general level
3.b: general gear
3.1: soldier
3.1.a: levels
3.1.b: gear
3.2: engineer
3.2.a: levels
3.2.b: gear
3.3: medic
3.3.a: levels
3.3.b: gear
4: unit builds- not done
4.1: soldier
4.2: medic
4.3: engineer

outside of missions you have 4 events every day. these are make camp (night), critical decisions (morning), strategic choices (afternoon), and tactical exploration (evening)

Making camp is the most benificial (usually) event. Here you will get to do most of your character building for the dun.

Codex- this option is where you level up your units every day. I will get more into each individual skill in it;s own section, but it is important to know there are 8 skill choices per row, and each row is one more expensive than the previous row. (to max out the first row 8 you need 8 skill points, to max out the second, you need 24 skill points, the third row requires 48. The forth 80.)
Crafting- this option is where you craft or replace your units gear, it is important to note, you do not save lost units gear and are not refunded. Each soldier has 5 pieces of gear that can be modded. Two weapon slots and 3 armor. I will have their own sections for these later.
Camping- Camping is the option to feed your units.
Meeting- Meeting is the option to boost morale
??? (do not remember the actual name)- this option contains either level ups or reduced agro
Heal- This option alllows your units to be healed

This choice can be either good or bad. the choices range from

airstrike- reduce aggro
vaccine- 5% research
To Be ADDED later

This is your mission select. they are categorized from D5 to D1.

I am skipping the tutorial heli here because it is super simple.
edit 1.01: I am changing CC, RC and LC to just C. I mislabled several when I first made this guide. (specifically RC as CC)

DC5 or defcon 5, is the easy stages, all in the demo. (in so far as they are easy compared to later) I will go into strats later, but for now I will list the maps I have found so far and how to do them (from memory)

restaurant- this is the restaurant, if you remember CE2, there is a cook in the base in the beginning with a pistol, he returns here already being escorted. south east corner of the map is a room with a electric motor to electrify your barricades (or cades for short). there is also a materal pickup in here as well. in the north east corner is a kitchen with a small food pickup and a stove to cook a meal for one soldier. outside the room is a large food pickup. to the south is a soda machine that also will feed 1 soldier, right beside the civ. to the north is the way to the back exit as well as a small food and material pickips. To the west is the door out of the building which you will have to open in order to get to the harder to use exit to the northwest that does not have a food penilty. Personally, I find the outside exit not worth it.
Normal run pickups: 2 full meals, 600 food, 100 material, 150 common components (or CC)
difficulty: 0.5 out of 10.
strats: cade bottom window, put civ and shotgun soldier behind it, loot everything and leave through back door.
gun shop- If you ever played resident evil 2, you know where this is from. the gunshop owner wants his things from the back room before he goes with you. with a slightly better shotgun than the starter default, he will kill a bit better than your soldier can. if you got an engineer there is a turret as well in the shop. as well as three ammo boxes (one of each type) and a CC pickup. in the back room to the west there is the shopowners stuff, and another 7.7 ammo box. Again there are two exits, first to the north through 2 doors or outside going east. Personally, I rather just go out the back.
normal run pickups: 400 7.7, 120 12, 1000 9mm, 50 C
difficulty: 0.5 out of 10
strats: get the shop owners stuff and move him to right side of counter, make turret if able, loot everything, leave via north exit
clothing store- I am not too overly familuar with this map but I remember there are 4 doors, west, NW, NE and east. along with various C pickups there is also a safe behind the counter and a power gen through the west door. the NW door leads to the worse exit, but if you got an engineer, the NE exit is better.
NRP: safe 1, ???
difficulty: 1 out of 10
strats: this map can easily get you killed if you do not know how to get out. Get safe and open NW door first before proceeding to loot.
pub-homage to shawn of the dead, this place has 4 civs and a soldier with a bat. If you have a medic use it to check the civs other wise use a soldier to cover the one doing the checking to minimize damage. The NE room has a power generator that will open the better route, to the north is a C, middle of the bar is another C, behind the bar is a safe, and there is a soda in the SW corner of the room. South door leads to a hall with two exits. South exit requires power, east exit has a zombie on other side of the door.
NRP: safe 1, C 100, 1 meal
Difficulty 1 out of 10
Strats: send engineer, if you got one to generator, medic to check civs, and loot everything. keeping your main powerhouse in middle of the bar. cade if needed and able. you can quickly become overran if not observant and careful.
pharma- there is a traitor amonst us. it is a guarantee that there is an infected on this level. infected from the north, NE has a research point, center has 2 med points, one to the west, one to the SW with a large C point. Door to west is bathroom with just dead in it. Door to south has 3 civs and a computer. rest of path out is straitforward.
NRP: 500 meds, 250 C, 5% vac, 1 pc
difficulty 1 out of 10
Strats: I recommend not coming here without a medic. despite seeming easy to defend, you can easily get overwhelmed here. if you find the infected you can use the soldier to help defend, but you are probably not going to be here more than 15 waves.
mechanic shop- the motherload in comps, to the door to the west is an electric gen. going clockwise is a large C, blueprint table, fuel barrel, then a door to the SE leading to another large C and the way out (needing a key), some RC to the SW and a door to the west. in the western room is the key on the table to the south and LC and RC pickups. in the middle is a civ working on a car.
NRP: lots of C, fuel, and a Blueprint
difficulty: 0.5 out of 10
Strats: if you got engineer, make turret and cade while others open doors and loot, power generator and keep an eye on cades, use soldier to reinforce as needed, and rebuild them as needed. after engineer gets defenses up, they can work on car as others work on looting and getting way out unlocked.
without engineer, get way out unlocked, hold out as long as able while looting, run when you red aleart.
electronic shop- I think this is reference to a movie, but not sure. 4 C collection points in main room, turret to the NE, only door to the NW, SW in the hall is door to backroom with shop owners 'friends' There are C in here and a blueprint
NRP: lots of comps and a BP
Strats: make turret and cade NE. send best unit to check on friends while others loot. send owner to cade once you are able, loot everything.

DC5 event (17 days remaining)- here you are in the sewers after the cutscene. this one is simple, outrun the fish, take down the 3 cades and get your people out. (and the civ) on normal, you require to have at least 35 second wave timer in order to get 5 + civ out, even then it will be close. having extra move speed on units would be good too. I recomend if you need a fish sacrifice, use a pistol soldier.
You can use sewer sides (north and south) to cut a second or so of travel time between cades.

these are the maps you get in the Defcon 4 stage of the game.

subway-this one is a duzy, among one of your first 'last stand' missions, I highly recommend you go silent on this mission if you do not have silenced guns yet. to the north is the enemy gate and going clockwise is a soda machine in the corner to a door to the east with another soda machine beside the inner pillar, a third soda machine is also here by the opposite pillar with several civs and finally a door to the west.
the door to the east goes to a hall full of infected and there are two door here, first is a door near the entrance to the hall that leads to an office with C and more civs. the other door is at the end of the hall and contains both gens and more C. the door to the west has another hall of infected and a 4th soda machine behind the SW most pillar. the only exit to the room is electronically locks, which leads to a quicker exit but with steeper penilties.
the quirk of this map is it takes about 5 minutes for the train to arrive. you got to both last long enough to do this while not causing a red aleart that will kill you. oh, also infected on the train too...
NRP- lots of civs, some C, 4 meals
difficulty- 2.5, last stand mission means you got to watch your noise output. halls of infected can be tricky to clear.
Strat- if you have not crafted a silenced weapon by now, you need to use a shotgun to hold the choke and clear the right side. otherwise your noise meeter will climb too high too fast and force you to either take the alternitive path out or fight a red aleart while evac over half a dozen civs.
police station- (my favorite map) this one you start in a central area and leave to the west, (windows to east is where infected come) I like this map because of all the ammo you can get from it. going clockwise, the door to your immediate south is the armory, which needs power, then a door that goes to another door that has the gens.
further south and on the opposte wall of the hall (SW corner) is a turret and a door that leads to a room full of infected and the back way out, continuing on that wall going north is a couple of offices with C and ammo in them as well as a few poi such as the cameras.
finally is the door to the hall to the north (with another sentry) hall is full of infected (noticing a theme) and 2 soda machines and is caded up. (hence why the two soldiers who could not get in during the cutscene) outside to the south is the main exit, but you got to fight your way to it. up to you if you want the agro more than the fight. at this point I took the fight because I was stacked on ammo.
NRP- tons of ammo, C, 2 meals and a few other things
difficulty- 2, should be easy enough to get the ammo and get out before you have any real problems. becomes a bit more tricky going out the main exit.
strat- if you have no silence weapon, I recommend ignoring the northern exit, get power asap, clear the evac and offices, and once loot area is clear, set shotgun soldier to guard window with cades and turret while everyone loots until done or RA. then evac out the back.
If you have silence weapon, do pretty much same thing, except ignore back exit and to go out the north hall, grabbing the 2 sodas on the way. make sure you kill the feasters before leaving yourself in a bad spot while evacing.
clinic- oh wow, a nightmare. okay, to start off, you are on the east side, the exit it to your east, but surprise, surprise, this is ANOTHER last stand mission. there is a coridore that goes east to west, going COUNTERclockwise from the east exit door, there is a soda right north to it then the first door on the right leads to two rooms, each containing a generator, the second door has infected behind it. following that there are three more doors, which lead to various clinic type rooms. all but one immediately have infected behind it (a theme perhaps)
you should know the game by now, lockdown the west infected interance, clear out room by room, loot and so on.
NRP- tons of meds, several tables containing interactives including tech and research for vaccine as well as cures for poison and bloodloss. SE most room also has a medstation you can make. oh, and the soda.
difficulty- 2.5 , narrow corador makes readusting units tricky, small rooms make it equally as hard.
strat- send anchor soldier and engineer to west cade, medic check civs, everything else gets power on, clear rooms then loot. take note, rain makes silence bar more to your benifit.
factory-the discription of this one is kinda off, at least I think so, not had it blow up on me yet, but you are kinda on a clock. you start on the east side, there is the exits here as well. there are 4 rooms + corador you are in. going counterclockwise, an office, gen room, main fuel storage and factory floor.
NRP- C, engineer BPs, and a bunch of fuel.
dificulty- 2.5, if you have things without resistance and armor (like engineer and medic) you might get them killed here if you are too wreckless or slow
strat- anchor the infested gate to the west, clear rooms and so on as normal. take note of the yellow barrels. shooting one will cause an explosion that might hurt or kill part of your squad. but worse, it will spike your noise by 1200. which is bad. you also got to keep an eye on the fire in the middle of the hall, it can grow big enough to kill units if unwatched long enough. I have not tested it to see if factory will actually explode or not. be kinda cool if it did. ;) ;) devs.
Library- you start in the south side of the main room here, yet another last stand map. lots of 'knoledge' stuff in this room. some C here and there, some civs. only exit to the north... after it stops raining. east side door leads to a hall with three doors, north side two has gens and C in them. south one is a trap.
On the west side is another hall leading to more knowledge and C. there is a soda machine to the far south of the hall and in the SW room is a 'map' interactive which will add 1 day to your defcon. north side of the hall is another infected enterance you can trap.
NRP- lots of unlocked gear, civs, and C, 1 meal and 1 day as well
difficulty 2.25, far easiest of the last stand maps in the D4 catagory, you got a lot more room to manuver here and the rain makes loud guns more forgiving.
strat- cade and anchor the south, get gens up in east side then clear west, keep a guard and an eye on that north area while you loot. trap does not always stop the infested
tin can assembly-by far the easiest D4 mission, maybe the easiest mission in the game. you start in the west side with common C and food, to the south is the gate for the infected. through two doors to the east is more food and common C. not much else here.
NRP- lots of food some coomon C
difficulty- 0.5, seriously, this is probably the easiest mission in the game... unless you are out of ammo... even then, very doable quickly, and has an easy evac to boot.
strat, anchor SW window, loot everything, leave... no need to linger... (might be a bad thing to lurk too long near a window or the center hall)
museum- the last mission of D4, cade at start, go through several doors in the building and get a split. door south is a security room. enemies here and some loot. after event in hall, look to north for a vent, a very nice safe and some ammo is in there, go through last door on west and leave...
NRP- some 9mm and 7.7 ammo, a few C, and a safe
difficulty- 1, can be tricky if you leave rear unguarded or do firepower to clear the security room
strat, anchor and clear, mind the vent for bonus loot, barely worth the time to do otherwise.

ran out of room in previous section for this... lots of words.

D4 event you are given 2 option here on day 12, stealth or run loud.
path stealth- this one you basically have a ton of stuff between you and the extract, near impossible not to attract them unless you have everything in fists BEFORE the mission. I prefer the other route.
path RLH- you have several baracades you got to go through, which is easy enough if time consuming, if you got a maxed out shotgun here, this part is no problem, as you can easily get to the 2nd portion of baracades where there is 2 sentry turrets. here you can keep your shotgunner (or another ace soldier) while the rest of your team clears to extract. I find this one much easier than the sewer mission, if not longer.

oh boy, we are now getting into the hard levels, hese have new unique enemies and 'alphas' aka bosses.

theater- not won this map yet. those bugs are super hard.
waterplant- you start in the NE corner of the map and go clockwise into the building. before I tell you how to get into the core of the building, I got to tell you about the utter pain that is this areas unique threat, stealth infected... yes, FML right here, they only reveal themselves when in or near water on the ground. keep your squishies outside with an escort by the outside door until you are sure nothing is inside. This mission will likely be by far the most cautious mission to date.
from the building enterance, hugging the left wall will get you to the core via doors and such, to the right is a locked motor gate, then a door to the gate's motor, then the gen to the far sW, this is one of those, you need a map missions and a more through guide. which I am not going to do. SRY!!!
LOOT- some fuel, some C and not much else.
difficulty- 4, definitely a mission you want to do just so you NEVER have to deal with these enemies in your run again.
strat- use one group to clear the building BEFORE you send in your squishies. serious, no joke, I have had maxed out soldiers die on this mission several times because of a moment of inattention. PAUSE OFTEN!
(side note, there 'might' be a way to detect the invis, but I have not found it, but I suspect there is one)
appartments- this is the boss from the armory mission from CE 2. centeral appartment complex, with rooms on the outside of a donut, three main rooms are in the W, N and E, which has infested nests, which keep alpha immortal. kill them then kill the alpha/ wurms are annoying and hard to shoot, extract is in NE corner.
LOOT- food, C, some meds
difficulty- 3.5, you got to keep an eye on the alpha as it moves around.it is an insta kill, side note, it can reach into some rooms via a weird animation clip when going around some corners, so keep squat well in a room.
strait up kill nests, kill alpha, clear and loot. mind the infinite wurm spawns. if alpha is left alive all infected get bonus hp.
mansion- this is another alpha from EC2, you start in the kitchen, in the east is a hall where there is a bathroom and a storage room on the south side, to the north is a bedroom with some civs and C.
to the left and north leads to a closset which leads to the alt exit. to the SW directly south from where you start is the gens for the map.
LOOT- some food, a few C, a little ammo and meds.
difficulty- 4 this is a mission you need a range weapon for. whihch is why you get so many civs with guns,
strats- make sure you position the civs with guns in a way they do not get hit (do not expose them to los strait through the windows, keep them to the sides. in theory you can beat this map without ever shooting, but that is unlikely and boring. side note, high level cades can survive a shot from the alpha (at least 80 hp)
lab-this one has another EC2 alpha, it a flower, you start in the north side where you have to go counterclockwise through the labs, personally I would rush this one in order to conserve ammo. in the middle of the facility (accessable via a vent near the first regen plant, it beside a pillar in the SE corner of the room)
You need to rush through the green plants in order to get to the alpha, in which you have to go to the sw room right before the self destruct room, and find a vent to the west, through the vent is a room where the alpha is located.. kill the alpha and the rest of the plants stop regenerating.
LOOT- lots of medical research, some ammo in the armory you can unlock later and a few C. 1 civ in the bomb room you can save and a soda in the security room.
difficulty- 4, you need to rush this one so you do not lose your progress. in addition you need to end the alpha before anything else, or you be stuck with endless regrowing plants.

occurs on day 8...
mental assylum- so this is the creepy AF mission, but fairly easy none the less. if you played CE 2 then this one should be no problem for you. linear path with one side door you unlock after you get the key for it at end of hall.

mouth enemies close after about 30 seconds, so make sure you do not become a jawbreaker to them, they killable if you clear out the rest of the stuff and get the key. not much in the side room but there is some LC and meds as well as a med table and poison/bleed cures

woo, made it finally to new area, the hardest yet

hospital-
depo- big courtyard full of stuff, doors to north and south, SW door has gen, NE door (behind motor) is other gen. NW door is an office, N door is fuel, S door is exit. E door got nothing.
lab 2-
school-
market
offoce

fuel plant
another linear path mission with a lot of cades blocking your way. nothing special for this one, periodic places for your own cades. near center of map on south side is 4 fuel drums hidden behind a fire. other than that not much else to this map

and here we are, the final stretch.

day 3- Mall

here you can get any missing resources you might need. I would focus on ammo as by this point I am pretty much maxed out.

you will get swarmed here at the beginning, just outside the mall enterance to the SE is some fuel and LC. either side of enterance is a generator as well. I highly recommend not building the far left turret as it is an ammo sinc.

two exits, first to the right via the NE door and through a hall, other exit is via a vent on the NW most corner.

day 2- civ evac

oh boy, I hope you got ammo. or save your ammo for your own evac. this mission ends when either you evac all the civs or the cade falls. first time I got here I managed to save 27 before red aleart... no ammo but 7.7 and a mild panic attack.

day 1- GTFO

so you are stuck on a streat, infected coming from every angle, and you got to fix your ride, you know the song and dance by now, watch out for secondary spawns from east side. interact with things that need to be and gtfo... or dont... there is an achivo for that too...

units are divided into four different categories.

Soldier- These are your main fighters, they carry weapons as their main and secondary ranging from knives and shields to fully automatic riffles and explosives. They also can be equipped with armor.
Medic-These are your healers, they have a 100% chance to identify infected civilians and have some kind of healing unit or booster as a primary and another one as a secondary or a gun such as a pistol or smg. Their armor gear provide your soldiers with food, morale or bonus exp.
Engineer- The engineer are your support and looters. They build barricades, make turrets, place down barbwire and can loot the largest containers in a fraction of the time compared to other unit types. Their armor provides daily ammo production of either pistol, shotgun or 7.7mm.
Civilian- these are on map recruitable npcs during missions that are the primary task to evacuate them. Take note that they can not interact with anything but the evac, some have weapons, but rarely can they take more than a hit or two before dying. They have to be evac before your last soldier as well, or they will be left behind.

general skills are skills anyone can learn upon a level up.
not done

Left:
close combat- close combat grands extra melee damage
Line of Sight- increases your max field of vision for a unit by a small amount
Health- increases max hp
Resistance- reduces the chance to be affected by fire, poison and bleed
Middle:
Speed- increases movement speed
hunger- fills and increases hunger bar of unit by 1
stamina- increases max stamina bar by a small amount and slightly increase recovery speed
Right:
Exp- Increases the amount of exp you get per action you take
Bravory- fills and increases your morale bar
loot- slightly increase the speed you loot
lockpick- decreases the time it takes to open a door by a small amount

I believe the only standard gear between all classes (but not confirmed) is the pistol and smg. (but never seen the option to have them on medic or engineer)

The pistol is a low damage, slow fire rate, medium accuracy and mediium range weapon. it can be upgraded with 5 mods

more on mods later

The smg is another low damage, medium range weapon, but trades accuracy for volume of fire.

soldiers have the least unique skills compared to the other two unit types
not finished
Left:
Penetration- minor increase to bullet damage
Middle:
Right:
Accuracy- minor increase to accuracy

Soldiers have the largest selection of gear to the other units.
not finished
Main weapon:
There are a total of four primary weapons,
Shotgun- the shotgun has 5 slots for upgrades. There are many ways you could build this weapon, but one I highly recommend is with piercing, as long as it has ammo and piercing it has near unlimited ability to hold narrow corridors. And is key to getting as many civs out with the evacuation. as a proper build soldier with a shotgun can kill 80% of the infected during this mission
Assault riffle- A rapid fire medium damage and mid to long range weapon with moderate base accuracy. Has the single damage output of the shotgun without the penatrating power, but with far better range. A good, I need a boost to firepower, weapon.
machine gun- The 'kill everything' weapon, highest dps weapon in the game (other than perhaps melee) and can have penatration as well. takes some time to set up and reload however. No better, oh crap button however when dealing with special infected like the bugs or dogs.
sniper riffle- The '1 shot 1 kill' gun with the longest potential range in the game. It takes time to set up and aim, but there is no better ammo efficient weapon than this. Good to use as a backup weapon when ammo is tight.
Grenade launcher
Secondary weapon:
These are considered the small arms.
Pistol:
Smg:
Knife:
Shield
Helmet: It has the most slots for upgrades among everything at six
The first collumn of upgrade consist of either an armor regen rate upgrade or +5 armor
The second column has three unique upgrades to it
1:
2:
3:
Armor:
The soldiers armor by default grants 15 points of shield and can be upgraded three times with either the option to increase the shield amount by an additional 15 points or increase the rate of regen
Backpack:
The backpack has three unique options to it
1:
2:
3:

The medic has unique skills that help with it's role

Left:
??? (do not remember name- this skill helps with all active effects of your doctor tools minus deployables.
Middle:
Rescue- increase the speed in which you treat civs
Right-
???- increase the effect of passives (such as armor mod bonuses and medpod deploy)

not done

Medipod-
Curepod-
boostpod-
medipad- unlike the others, the medipad is a deploy-able. which means you can set it up then have units heal on it while the medic does other stuff.
1:
2:
3:

the list of unique engineer skills
not done
Left:
Crafting- increase the ammount gotten from engineer armor mods
Middle:
Building- increase speed you build and repair sturctures
Right:
Looting (not to be confused with loot)- increase the amount you loot from a container by 1 per level.

not done

Turret- deploy a turret in a 3x3 clear area, instantly consumes 100 rounds and need 100 more to continue functions
spotlight- reveals and slows nearby enemies, including groups
barbwire- a limited deployable that can be upt anywhere accessable, even in baracade spots. Made to slightly damage and slow down the emeny
Ckit- Gives a flat bonus to all baracades you can make.

soldiers are a versitile class compared to the others, this is namely because they have a wider assortment of weapons.

To be continued

so, there are three options for medic gear and about the same in the number of builds.

The first medic build is full on healer. These have either the healpod or healpad and the curepod. (pod is held device, pad is the deployable)

These medics focus on the knowledge skill before everything else. (cure if they are the pad user)

The second medic build is the buffer/healer. Again they have the healpod or pad but their other tool is the stimpod.

Again these medics focus on knodledge.

The third medic can be either or either of these but choose different armor mods.

The first two medic classes usually have a mix or match of vitamins and happy pills to keep food and morale high while maybe having 1-3 books for bonus global exp per day.

The other type of medic is the opposite, having at most 2 food and a morale booster and putting everything into exp bonus. In addition those that do this make it top priority to get their medics this build before leaving DC5 for maximum effect.

engineer is probably the most broken leveling unit in the game. the way experience works is each action of gathering nets you X exp. Each exp bonus you aquire via gear or skills nets you at minimum 1 additional exp per action. simple right, and not overly broken.

Here is the thing, each individual item you gather = 1 action. If you gather 10 9mm ammo, that is 10 actions. now, where the engineer gets broken is it can add +1 action/gathered res at a time every time you gather something. so 1 becomes 4 if you have 3 in looting.

The most obvious broken build is to work on this fact.

Max out loot, looting and exp bonus asap. IGNORE EVERYTHING ELSE IF POSSIBLE!!!(all right side tree skills first)

Ignore lockpicking in favor of nearly everything else. Resistance and move speed should be your next priorities or first picks if the alpha choices are not present. (max out resistance makes you immune to fire.and poison)

Next after those 5 perks should be crafting with building as a secondary. after this anything works.

As for the gear, it largely depend on what your soldiers use as weapons. but I typically go for 6; 7.6mm ammo generators and 3 shotgun generators.

My preference is barbwire and baracades, but there are cases for spotlight and turret too. there is not really much variance you can have with the engineer.