You select quirks while creating your character. Each one of them is an upside and a downside, at the same time. They offer bonuses and threaten you with high penalties. Each character can have one quirk, at most. Choosing any is optional.
Quirks have been prepared in a way that makes them both useful and extremely burdensome. Some of them start providing you with a bonus only later in the game. Others are good and bad, in turns. The effect of some other are completely random. They can affect skills, attributes, or specific combat situations. There is nothing like the best or the worst quirk. All of them are equally pesky and useful. The key is the character that you endow with such a quirk. , because only several of them affect the entire party. It is a good idea to get one, if you know what you are doing, you have a plan on how to develop your character, or you know how to exploit the upsides, while avoiding the downsides. Otherwise, it is best not to pick any.
No Quirk - The basic state. The character does not receive any quirk.
Ascetic - It offers 5 skill points and 1 attribute point, in exchange for the inability to use gadgets. Therefore, it offers a high bonus at the beginning of the game, which makes it easier to complete initial quests, however it is difficult to predict its effect on further gameplay. All depends on whether the character will be using gadgets that boost skill or attribute level. The gadget that increases the chance of dealing critical damage may be useful, but you can do well without it. The gadget boosting the Smart Ass by 1, boosting the max carrying weight limit or increases the maximum of carried water may be key to complete a quest or to get to a location. Especially so, if the character has more than several key skills and may obtain a gadget that boosts two of those skills. The problem is that not all the skills have their gadgets and later into the game, when your party will be sufficiently experienced, you may have no need for them. Apart from that, while exploring the game world, you can simply fail to find them, or find ones that you will have no use for.
It is therefore a good idea to take this quirk for characters that are constructed for combat only and have skills that cannot be boosted with any gadgets, or which do not need those. Also, it is a good idea to take it, if you are short of points for important skills, or the beginning of the game is too difficult for you. However, if you want to be able to use gadgets, or you fear that at some point they may prove useful to you, it is better to pick something else.
Asshole - A problematic one. In the game, there are three social skills and this quirk makes it impossible to access two of them, whereas it grants 100% success using the third one. It ay seem a fair trade-off, but there are quests that you can complete in an amicable way, only with Kiss Ass or Smart Ass. The lack of access to them will save you some skill points, but it limits your options, in the long run, and makes the party fight, where a talk would solve the problem. It is a good idea to take it, if you are going to beat the game using force, but otherwise it is better to pick something else.
Disparnumerophobia - At even experience levels, the character gains +2, and at odd ones, they lose 2 points to all attributes. This means that the number of your skill and CON points will be subject to change, so will your AP, and each level you progress, your character will receive either a rise or a drop. You an use this in many ways, by creating characters with less important attributes, at the level of 1, thanks to which the penalty will not be as pesky, and you receive several extra points, at the beginning, to distribute among the attributes. Tanks to this, you will also be able to save up points later into the game, when you need to develop attributes to level 8 and wait for the character to reach an even level. This does not change the fact that your character will be stronger an weaker, in turns and as a result, their usefulness will also fluctuate. It is a valuable quirk, if you know how to use it, but very risky otherwise.
Way of the Squeezins - It provides you with additional AP and damage, when the character is affected by the squeezin and it provides you with a penalty to combat speed and critical hits, if they are not. You can only find squeezin every now and then and the duration of one serving is 300 seconds. This means that you need to drink it before each fight start another one right after the previous one has finished and you have to maintain a supply of alcohol. Otherwise, your combat value drops a little. Of course, you can take this quirk for a non-fighting character, but in practice your party are fighters and for this reason, it is better to find something better.
Thick-Skinned - A +2 Bonus to armor, at the expense of combat speed. It may not seem to be, but it is a good trade-off for a tank character, because what they do is stand in front of the rest of the party and take damage. Therefore, it is a good idea to take it for the character who is to perform that role. For example, for a specialist in assault rifles, or sub-machine guns, when fights away from the rest of the group, but close to the opponent. In combination with appropriate traits, and good armor, only machines are capable of wounding such a character severely, but still not all of them.
Animal Husbandry - Bonuses from the animals you keep are twice as high. It is a good thing, thanks to which taking care of a goat provides you with +2, to an attribute, instead of +1. The hidden flaw is that it provides a random chance that an animal will explode. If you are prepared to lose animal bonuses because of bad luck, and one of the character's skills is Animal Whisperer, this quirk will definitely come in handy. As for others, this one will be useless.
Fainting Goat - 35% of chance of fainting after a critical hit is useful in the case of fragile characters that require protection. On the other hand, the fact that they skip to the end of the queue means that, with a bit of bad luck, they can get to perform an action in a turn. Select this quirk if you cant to randomize your game. Otherwise, pick something else.
Mysophobic - a quirk that requires careful character selection, but on that can work miracles, at times. A bonus to healing, in combination with certain traits can save up lots of first-air kits and, as a result, also scrap metal and room in your backpack. The downside is that the character needs either high dodging chance, or sufficiently thick armor, which either prevents them from taking damage, or from taking much damage. This is so, because such a character, if hit, needs to use pills, or needs to be tended by another medic, which requires two of them on the party. If you are going to have two, one of them may pick this quirk. If there is only going to be one, it is best to make sure, first, that he will be able to survive any battle without healing items and the rest of the characters will not need to be healed during fights.
Heavy Handed - This is a good quirk for a character intended for melee. The penalty to deal critical damage is painful, but with a sufficiently strong weapon, and appropriately picked skills and attributes, this will not be as annoying. However, if you want to be lucky playing dice, it is better to pick something else.
Brittle Bones - A useful quirk for a character who does not need to move too much in combat, but requires as many AP as possible. For example, snipers hidden at the back of the party, or energy weapon users, who need lots of AP per turn. With high number of fighting characters, its effect becomes smaller, but in spite of that, 2 additional AP may prove to be sufficient for an additional shot. For melee characters, this will be annoying, rather than an upside. They are not going to need additional AP, if moving among opponents is more expensive. It is worth picking, if you have the right character for that.
Opportunist - This is yet another problematic quirk. It can be useful for every character designed to finish off targets, such as sniper with low initiative, but in practice this will only matter in combat with opponents with lots of CON. For example bosses or stronger machines. Opponents with low CON will either die, before the character uses the bonus or will be so low on CON that they die in one shot/blow. For this reason, this one is a context-reliant quirk and it may prove useless throughout most of the game, but it makes fighting more demanding opponents easier. Especially if the character also has high level of fighting skills and good weapons.
Delayed Gratification - This quirk provides you with bonuses only later in the game, after the character reaches above level 20. At levels 1-10 the character loses 10 skill points, which they regain at levels 11-20. Additional points start coming with level 21. Considering the fact that characters can reach as high as level 50, this gives you as many as 30 additional skill points. As a result, the character will be weaker at the beginning of the game, which changes as latter half of the game.
The entire problem with this quirk is that a character with few skills is not going to need the extra points that it offers They will be more useful to a character with many skills, but because of the meager of points, it will be useless at the beginning, to the rest of the party. Because of its weakness, the difficulty level of the game goes up. Later on, additional points not only let you make up for that, but they also boost the usefulness of the character. Also one with few skills, because the additional points allow you to buy new skills and to develop them. For this reason, it is a good idea to pick this quirk with characters of multitude of skills in mind, who are supposed to prove their worth later into the game. You only need to take into account the fact that you will not benefit from it, for a long time.
Unlucky - A random character gets lightning struck during battle. Random character means a randomly chosen character in the battlefield - allies, opponents, neutral characters. Lightning bolt deals quite a lot of damage and therefore can kill severely wounded characters. This one is a completely unpredictable quirk and it is a good idea to pick it, if you want to introduce another random element into combat. However, it may happen that you will not see, or feel, its effects, for a long time.
Psychopath - Chance of regular and critical strike rises with each accurate hit and it is lost with each inaccurate one. At the beginning, this quirk is annoying but with time, after the character has developed their skills and gains better equipment, it may prove highly useful. It is a good idea to pick it for the characters intended to have high chances of critical hits, and with later stages of the game in mind. At earlier stages this will impose penalties, rather than bonuses.
Manic Depressive - A quirk that makes the game easier and more difficult, in turns. It can affect the number of skill or CON points that the character obtains with the next level, chances of hitting the target or the speed of movement. For example, you can take it for a character with 7 Intelligence and hope that they receive a +1 bonus before leveling up, which ensures an additional skill point. Apart from select situations, the quirk is only to increase randomness of the game and if you want to, you can take it. Pick it also when you find a way of taking advantage of it, for a character with a specific set of attributes. Otherwise, ignore it.
Two-Pump Chump - A quirk useful against small groups or weak opponents. The more opponents, or the stronger they are, the lower the chance of ending the fight quickly, alongside the usefulness of this quirk. You will especially suffer from that while fighting with bosses, or big robots with lots of CON. It is therefore a good idea to give this quirk to the character with high AP, capable of killing two, or four opponents during a turn. However, if you want longer fights requiring tactical approach and careful elimination of opponents, it is better to pick something else.
Repressed Rage - After they take a critical hit, the character starts dealing more damage and has a greater chance of a critical hit. Instead, they never take a critical hit, but something worse instead. In other words, first they get the beating, but then they repay in kind. The quirk is useful, on the one hand, but at the other, all of that comes at a high cost. You can pick it, if there is nothing better, but there are better and more useful quirks.
Twitchy - A bonus to the base combat speed at the cost of lower chance of hitting the target. The cost is 10%, and you can alleviate it by crouching. Additionally, later into the game, attribute levels and skill levels will be high enough for this cost to be made up for, even without crouching. For these reasons, this quirk is a good one for a melee character, thanks to which they will be able to move quickly around the battlefield. Very useful, if the character is wearing a heavy armor that restrains movement.
Raised in the Circus - A bonus to dodges is tantalizing, but it is only 5% high. At the same time, a bonus to hit that results from the Leadership skill may be as high as 20%. Of course, later in the game, it is going to be easier to boost the chance of hitting the target but still, the penalty seems too steep, in comparison with benefits. You can pick it for a melee character, or for a fragile one that requires protection. Still, there are better and more interesting quirks.