I had noticed that there aren't many guides for the surrounded mode but that several seem to have issues getting the necessary 10k score in order to unlock the defib. It seemed that a guide could be helpful.
First things first, many players will beat this mode only to discover that they didnt get enough points to unlock the defib in doing so. So let's familiarize ourselves with the scoring system and go from there. You get points based on six different categories: Rations, Petrol, Trap Damage, Combat Kills, Survivors, and Karma Bonus.
Rations: this score is based on how much food, and possibly water, you have left at the end of the game mode. The survivors don't eat a lot, there are only two of them, so the only ways to really lose a significant amount of food is to trade it off or to have it stolen by raiders.
Petrol: This score is based on how much gas you have left, like the food you are most likely to lose this due to trading or raiders. There are several ways to additionally reduce fuel expenses in order to save extra as well.
Trap Damage: This is a score for how much damage your traps end up doing in defense of your base. Traps are of great significance in this game mode as you will be experiencing raiders nearly back to back in steadily larger and more difficult waves, punctuated by boss raiders throughout. It should be noted that trap damage seems to score slightly more than combat kills, so reliance on traps is beneficial in this game mode.
Combat Kills: This score is based on the raiders you kill during combat. There are many risks to engaging in combat but the raiders will steal resources from you if allowed to leave your bunker alive, and since resources are also a base aspect of your score, you can't allow that to happen unless you are 100% certain you stand no chance of winning (which we will cover how to prevent that later in greater detail).
Survivors: Survivors is pretty straight forward. You get graded on how well you managed to keep them alive. If everyone is alive and healthy you get 1,000 points. So keep this family healthy.
Karma Bonus: Karma bonus is a little confusing to some at first, but it's based on the decisions you make as the dad character in the wasteland. Each time he ventures out he encounters some form of moral dilemna, ranging from irradiated people begging for meds to a weird dom guy trying to compel you to fight his slave for his pleasure. Essentially you get more points if you are kind and helpful.
When you first start surrounded you have a fully decorated and mostly well stocked bunker. there is an excess of important resources such as food, water, or gas, but other resources are relatively limited at the start. You start with no proper weapons (though a board or pipe can be used it is ill-advised), and very little nylon or rope for traps. However, the game does provide you with other items that will be useful later such as the ammo press. You can deconstruct a lot of what is originally in the bunker, such as the excessive amount of beds or the second stove but it is not actually required to do so. It's more of a personal choice, you can choose to invest the time for the extra resources and space that you will probably find only mildly beneficial, or you may choose to focus on other tasks such as training your survivors with the punching bags so they do well in the fights they will be constantly in later.
I advise starting the game in the slowed time so you dont waste much time while you rearrange your shelter. Experienced sheltered players probably already know the layout and playstyle they like, but for those who havent fully discovered how they like to set up there are some aspects that should be kept in mind. Most of the raiders, excluding the bosses that get cutscenes announcing their soon-to-be attack, are there for the players resources. The raiders will bee-line for a given resources storage, for water they go for the medium water butt, for food they normally go after the small pantry but might go for other pantries, and for your items they generally go for the small cardboard storage box. You can shape the route that the raiders take to reach these resources by positioning those access points in specific areas. the raiders will always take the most direct path to the resource they are after. The raiders will ignore all other areas of your bunker that do not contain lootable resources, so it is best to keep your main living area seperate from these resources so you have a safe place if you choose to avoid fighting. I normally keep my bed, shower, bathroom, and skill items on the second floor down, on the right side of the ladder. while the kitchen, water butt, and storage is on the left side of the ladder. You want the area that your survivors will be in most, like the beds, near to the surface and your traps so that you have time to reach and arm traps when attackers are incoming, and so that you waste as little time as possible climbing around ladders to maintain your base or survivors. For this reason I only really use the first two floors at the start and put most of the larger storage such as the boxes, large pantries, and water butts, on the lower floors to be forgotten. Later game the third floor will also be used, but for things i only mildly pay attention to such as the ammo press and lab that you start with or in later game the water condenser or the recycling center.
Once you have your base arranged the way you like, there are some immediate resources that should be built. The shelter does not come with a mop and bucket, so remember to make one. A dirty shelter will draw rats and cause your survivors to become sick, making surviving just that much harder to do. You will start with a limited amount of nylon and rope, so i would advise using your intial stock for it to make the spike traps, a snare on the surface, and the tripwires to arm said traps. You may also choose to make the effecient toilet to save on your water in the long run, but will have to wait to make the efficient shower alongside it. Whenever you are not handling base or survivor maintenance, or prepping for the next attack, you should have your survivors using the punching bag. they will constantly need to fight, so the better they are at it, the more likely they are to survive and the better weapons they are able to use once the father finds weapons for them.
With the premise of surrounded being that you are surrounded, there is a lot of combat involved. You will face increasingly difficult waves of raiders that each end with the attack of a boss raider. The regular waves of raiders behave normally and seek out your resources, fully willing to ignore you if allowed but the boss raider wants a fight so be prepared. In surrounded, the start of your defensive combat is your traps. Early in game this will be spike traps, then you will get shotgun traps, and eventually you will be able to make the rifle turret trap. Because traps are so important to your defense, nylon is a godsend for your survivors as it is the resource you will constantly be low on for tripwire production. Keep an eye out for leather, especially if you didn't set up a snare so you can't catch your own. The leather will be used for armor, you have access to the teir four crafting from the start of the game so I would advise saving up for that vest instead of wasting resources on the lower teirs earlier on. Another resource to keep in mind is cordite, it is used to make shotgun shells, rifle ammo, and the pipe bomb (which is optional. You do not need to use the pipe bomb or make it, but I prefer to have a backup plan in case the fight doesnt go as planned). Whenever you have free time, train your survivors on the punching bags until they are maxed. it is easier to max out the mother's skills so you may not finish training cole, but diane can then be in charge of base maintenance while he focuses on training.
Your Doors: They will get broken, every time. upgrading your doors in surrounded does not deter any of the raiders, it only buys you extra time in which to arm your traps. For this reason it is entirely up to you how you manage your doors. if you dont need much preperation then you may only repair your door enough to turn the siren off. If you have a lot of traps or have traps on multiple floors that take time to reach, then you may consider upgrading just one of the doors. I would not advise taking the time to repair both doors each time, the frequency of the attacks makes it pointless and wastes time you could be using to train your survivors or keep your bunker running. So upgrade whichever door you plan to keep repaired, according to the time you need to prepare your defenses.
Combat Priority: this one is fairly simple but multi-faceted. it's a rather basic version of mechanics used in most turn based combat games, but for those unfamiliar with turn based games, you need to choose your targets carefully. Traps do add another layer to this, as they may injure or kill some of the raiders dropping a normally high priority target to a less substantial position. Generally speaking the idea is to attack the enemy who can do the most damage to you, first. Their weapon is the largest factor, but be aware of who has armor and what their health is as well. The mother does the most damage, and will generally always be stronger than the son unless you train him extensively more than her, so she would get the best melee weapon and would be your hard hitter. Once it is possible, i prefer to arm her with the axe (the only time i have encountered the axe in surrounded was during the dads trip when he encounters the man attacking the dog, if you offer to bring the man with you he gives you his axe and will bring your carry slots to 44 from the next town onward) and give Cole the knife. Firearms are of greatest priority, they have the ability to possibly kill one of your survivors in a single turn, so if you can't end the battle quickly disarming might be a better option. If the disarm fails though, you essentially wasted a turn. The sledgehammer and axe are the hardest hitting melee weapons you are likely to see, so they are next, then the baseball bat, the knife, planks/pipes, rocks, and finally unarmed individuals. If you have a situation where someone with an axe is heavily injured from your traps, and the other enemy has full health and a knife, you may choose to target the knife wielder with the mother before you can attack the axe-weilder, as cole does less damage but is fully capable of finishing the injured raider. Keep in mind that bandages only stop bleeding, first aid kits restore health and stop bleeding.
This is based on the beta version, so changes might have been made that makes this irrelevant. While it is obvious to take out raiders who are low on health due to traps or highest damage first, the problem many encountered is deciding who is the major threat.
The difficulty of each raid increases... Or so you might really think. It actually decreases because while the weapons they bring in are stronger, their stats don't change. And when they don't have enough strength for those weapons [they use them less effectively].
The priority, assuming you can one-turn kill, would likely be raiders with the mid-tier weapons, such as Hatchet, Knife, Crowbar and Rock. These weapons don't require much strength to fully utilize their damages. In addition, Hatchet is capable of a one-turn-kill if you are unarmored.
Next in line would be INJURED firearm raiders. With the exception of the boss, enemy NPCs never fire unless they are injured. Even then, they may still not fire, but you will not want to risk it. Prioritize pistols, these guys have 12 chances to kill both of you, while shotgun only has 6 and rifle with 3. Tier 4 armors block 3 shots, so you are mostly safe.
Finally, go for the sledgehammer/rebars. Leave uninjured firearms for the last, but if they become injured due to a counterattack, they become top priority again.
If you need to juggle healing and fighting, disarming the last raider lets you have a free turn, since they are scripted to pick up their weapons about 90% of the time. You can use this time to heal up with First Aid Kits. The emphasis is on traps now, seeing that Cole's Courageous trait was removed after beta ended.
Scavenging, Trading, and Karma
The surrounded family does not possess a radio and the only one scavenging is the father, who returns to the bunker every 10 days, finally bringing a camper on the 50th day when the game mode ends. The only way to obtain external resources is through the father scavenging or the trader who stops by the bunker a few times (I honestly didn't keep track of the exact days he comes by, but he seems to visit in between the fathers trips for the most part).
Scavenging: Most of what the father can get is only mildly usable, but there are some items that you should grab whenever you get the chance to. Nylon, rope, cordite, bulbs, and leather are of particular interest, leather moreso if you did not set up a snare. You may also be interested in collecting motors (freezers), batteries (reduce gas use with efficiency generator upgrade and solar panels), wires (recycling center and water condenser), and pipes (general crafting item, can double as a weapon, can help with water usage items) depending on what you plan to build. Weapons are incredibly useful, but you can't equip the dad or his possible companion, so you are mostly focused on finding good weapons for the mother and son as well as firearms for the traps. Always grab ammunition, even the pistol ammo can be useful, especially during the final boss if you haven't trained your characters extensively. Extra weapons can be traded without giving up the resources that count towards your final score (petrol/food). It may also be worth collecting teddy bears, records, and books exclusively to trade with, assuming you have the room. Whatever else you want is mostly just your own discretion and resource management. You can get workbench tools but I honestly prefer not to, it speeds up repairs and building but I prefer to gather other resources instead.
Trading: Once in a while a trader will come to the bunker and buzz at the intercom. He generally carries a decent assortment of goods, which seems to always include some of the resources you need most like nylon, rope, and leather. He will also offer firearms, but it is generally not worth it to buy them as the father will usually find plenty with patience and they are expensive. remember not to trade your petrol or food, as those count towards your end-game score and allow you to unlock the defibrillator. I personally prefer to collect books, teddy bears, and records to trade with the trader, occasionally extra weapons or meat if my freezer is getting too full to be able to collect more snares.
Karma: Karma is obtained based on the players choices during the fathers trips. Some of the events can result in good karma and in-game benefits, such as when you encounter the man attacking a dog. If you offer to bring the man with you it results in good karma, he gives you his axe, and he will raise your carry slots to 44 starting at the next town. Others are a choice between resources and karma, such as the weirdo with the slave. If you fight and defeat the slave for his entertainment you get 9-10 of each ammo type, but if you refuse to fight the slave you get karma instead. Other choices include fleeing from the "feral" children, giving a "feeble" (half-dead) person anti-radiation tablets, or giving an eccentric scholar lenses to read with. Each has an option that does not grant karma (kill the kids, kill or leave the feeble to die, steal the books or kill the reader) but karma contributes to your end score and the in-game rewards are generally not worth it. Though some may consider taking the reward option on the slave event for the ammunition as it can be difficult to get large amounts of ammo and very helpful for survival.