Core Mechanic Version 2
Any non-trivial task has a difficulty level, a duration, and an intensity. A player attempting a task has a skill level, an attitude, and a strategy. In general, all attempts require effort, whether or not they are successful. The amount and kind of effort required is a function of the tasks's duration, the tasks's intensity, the player's attitude, and (sometimes) the player's strategy. A player will succeed at a task if and only if his or her relevant skill level (plus a die roll) is equal to or greater than the tasks's difficulty. If the skill level plus the die roll is only slightly below the difficulty level, then the failure can be converted into a success using "suckage points," which usually involve spending additional time or money. Ordinarily, failures simply waste the player's time, effort, and materials -- with sufficient resources, players can try a task again immediately after failing. However, an especially bad failure can cause an accident, which may break critical components, offend critical allies, or seriously wound the PCs. Moreover, some tasks may be so difficult relative to the player's skill level that even repeated attempts will not create any real likelihood of success.
Why Use This System?
- It relies on the same core mechanic for all aspects of play, including combat, travel, negotiation, and mechanical prowess. This frees up space in the rules for expansions based on setting-specific features like magic, quantum physics, ninjas, etc.
- It prevents players from singlehandedly defeating an unlimited number of opponents, no matter how powerful they get.
- It allows players some choice in how hard they want to try at various tasks, while also forcing players to react to unexpected effort expenditures
- It makes accidents (on both offense and defense) more likely as players get fatigued
- It avoids the awkward use of GM authority in the old system where players are artificially prevented from trying again after a failed roll, while still discouraging endless repetition
- It accounts for the difference between a *tiring* task and a *challenging* task.
- It disposes of routine cases routinely, with no more than two die rolls.
- It allows for a bit of depth and excitement when something goes spectacularly wrong.
- It lightly penalizes attempts to perform tasks that are too difficult, just enough so that reasonably brave players, on average, are no more or less successful at life than reasonably cautious players.
- The more complicated features, like variable effort and combat strategies, can be safely ignored by players who aren't interested in them -- they can say "I attack" and the GM will tell them how much effort they spend
Difficulty reflects how complex, counter-intuitive, risky, or advanced a task is. Very difficult tasks simply cannot be accomplished by untrained individuals because they will (a) not know what to do, (b) make critical errors, or (c) have a body or mind that is too weak or uncoordinated to successfully complete the task. Accomplishing a difficult task thus requires significant ranks in one or more relevant skills.
Duration reflects how long the task will typically take to complete -- second, minutes, hours, days, etc. Although sustaining a task for a very long time can sometimes increase the difficulty level, the main effect of extra duration is to increase the effort required to accomplish the task. A typical high school athlete, for example, would find it no more difficult to walk at an average pace of 3 mph for 6 hours than to walk at 3 mph for 1 hour -- but walking for six times as long will take six times as much effort. If the difference in duration is more than an order of magnitude, the kind of effort required may shift as well…for example, running for 2 minutes would deplete Wind, but running for 2 hours would deplete Stamina, and running for 2 days would probably deplete Health.
Intensity reflects how much attention, effort, or exercise is required to attempt to engage in the task. Swinging an appropriately weighted baseball bat, for example, is inherently a more physically intense activity than swinging a typical mini-golf club. Playing chess is likewise inherently more intense than playing checkers; there are simply more mental variables to be considered. Intensity will sometimes, but not always, vary with the skills of the person attempting the task. A 15-year-old, for example, will often find driving a sedan through moderate traffic to be Strenuous, whereas a seasoned trucker might find it to be Relaxing.
Note that for any given task, difficulty, duration, and intensity can all vary freely. One can imagine a task that is difficult and long, but not intense (spectroscopic analysis of an unknown chemical). One can likewise imagine a task that is easy, of moderate length, and very intense (running a six-minute mile in a business suit). A task could be of moderate difficulty, very short, and moderately intense (extinguishing a kitchen fire with a fire extinguisher). Thus, although difficulty, duration, and intensity are all positively correlated, no one variable fully determines the value of any other variable.
Players can choose to adopt various attitudes toward their task -- a PC could put in a relaxed effort, an ordinary effort, or an intense effort. Trying harder will consume more effort points and provide a modest bonus to the player's baseline skill roll, enabling him or her to accomplish slightly more difficult tasks at the cost of growing tired more quickly. Slacking off will conserve some effort points at the cost of a penalty to the player's baseline skill roll, enabling him or her to accomplish more tasks in the same day as long as the tasks are relatively easy for that player or the player is willing to accept a higher risk of failures and accidents, and disasters.
The 'baseline' difficulty level is 10, and the baseline skill roll is 1d20. A DC of 10 means that the task can usually be accomplished in a few tries by an untrained person of ordinary ability. A DC 10 task poses no real danger to a untrained person of ordinary ability -- as long as the novice is paying attention, the worst thing that can happen is that the novice will waste some time and energy. Examples include doing laundry, assembling a cabinet, reading a map, solving a local crossword puzzle, and training an overenthusiastic cocker spaniel.
Success, Failure, Suckage Points, and Thresholds
To accomplish a task, the PC first spends effort points based on the duration, intensity, and desired effort level of the task. Then, the PC makes his or her skill roll. If the skill roll plus any bonus or penalties from the player's attitude is greater than or equal to the difficulty level, the player succeeds. If the adjusted skill roll is a few points less than the difficulty level, the player may wish to spend suckage points to partially accomplish the task. The player might succeed at the cost of, e.g., taking more time, spending more money, or delivering a product or result that is substandard or missing some of its features. Suckage points are geometrically cumulative when chosen from the same category. For example, three suckage points accounted for by increasing the cost of the materials used would result in a cost increase of 2 ^ 3, i.e., paying 8 times the price. It is thus rarely advisable to spend more than three or four suckage points on the same attempt, as it would usually be more productive to simply let the attempt fail and try again.
If an attempt fails by 10 points or more, then, regardless of whether suckage points are used to help compensate, the player will have to make an addition roll to try to protect against the risk of an accident. Accidents take a form that is appropriate for the context and a severity that is based partly on chance and partly on fatigue. E.g., in combat, an accident might involve strained muscles, broken equipment, or even friendly fire. In negotiation, an accident might involve stuttering, offending an important client, or tipping a loan shark off to just how desperately you and your crew need a fresh source of credit. When assembling a radio antenna, an accident might involve breaking some of your spare parts, dripping battery acid on the ground, or irradiating everyone within five meters. Typically, your accident roll is simply 1d20 minus your total relevant fatigue. E.g., if you have -2 Wind fatigue, -1 Health fatigue, and -3 Focus Fatigue, your roll would be 1d20 - 6. A major accident (the kind that can ruin your whole day) requires a negative result for your roll. A moderate accident (the kind that can make you wish you'd never started the task at all) requires a result of +4 or less. A minor accident (the kind that is annoying, at worst, and can only really hurt you if it happens over and over again) is triggered by a result of +10 or less. If you roll +11 or better on your accident check, you manage to get by with a simple failure, which wastes your time and effort but has no lasting consequences. Players can get small bonuses or penalties to their accident rolls by selecting characteristics that offer the special "cautious" "klutzy" "lucky" or "unlucky" features.
If a player succeeds in accomplishing an attack in combat, then whoever the attack is directed against must either attempt to defend or take massive damage (Stamina Damage for deliberately nonlethal attacks such as tasers and full nelsons; Health Damage for potentially lethal attacks such as knifes and blows to the head). There are usually a variety of possible defenses, such as retreating, dodging, covering, shielding, etc. Each such defense is treated like any other task -- it has a duration, an intensity, an attitude, and a difficulty. If the defender rolls equal to or better than the required difficulty check, then the attack is blunted, and has no consequence except to make both the attacker and the defender somewhat more fatigued. However, in the event that a defense attempt fails, there are slightly different consequences. An ordinary failure ("the first threshold") will result in a 'flailing defense' -- the defender desperately writhes or leaps to get out of the way of the blow, blade, or bullet. This costs a significant amount of effort -- probably somewhere between 10 and 30 Wind -- and may cause one or two Stamina damage from strained muscles, etc. A defense that fails by more than 10 points ("the second threshold") will result in a flesh wound -- the blow, blade, or bullet will at least partially connect with its intended victim, causing several points of Stamina damage and a few points of Health damage. A defense that fails by more than 20 points ("the third threshold") will result in a critical hit -- a killing blow that causes dozens of points of Health Damage if the attack is meant to be violent, or an incapacitating blow that causes dozens of points of Stamina Damage if the attack is meant to be nonlethal. To avoid a threshold, players may spend suckage points. However, suckage points spent in combat deal with falling prone, damaging equipment, being disarmed, being stunned, or interposing limbs -- not with spending more time and money. Moreover, it is not possible to take more than two suckage penalties in combat on the same defense attempt, so a sufficiently strong attack *will* kill you regardless of how many daggers you throw out of your pockets in an attempt to be "disarmed."
This task is typically:
Relaxing -- light exercise; a good way to unwind; just enough effort to stave off boredom
Challenging -- moderate exercise; a good match for your abilities; conducive to "flow"
Strenuous -- hard labor; a severe test of your abilities; draining or even unpleasant in large doses
You approach the task with a(n):
Casual Effort -- you are barely paying attention to the task; your mind is elsewhere; you are unconcerned. -4 penalty.
Ordinary Effort -- you take the task seriously yet you are still aware of your surroundings; you are engaged.
Intense Effort -- you focus your passion and energy on the task to the exclusion of all else; you are obsessed. +4 bonus
Relaxing, Casual 1 effort
Relaxing, Ordinary 2 effort
Relaxing, Intense 4 effort
Challenging, Casual 2 effort
Challenging, Ordinary 3 effort
Challenging, Intense 5 effort
Strenuous, Casual 3 effort
Strenuous, Ordinary 5 effort
Strenuous, Intense 8 effort
The task involves:
A single, well-defined procedure or gambit; takes place in a matter of minutes (Wit / Wind)
A combination or series of steps; takes place over a few hours (Focus / Stamina)
An epic accomplishment or grueling perseverance; takes place over a day or more (Sanity / Health)
Typical 'defensive' tasks include
Jog 1 mile (Wind, Relaxing)
Run 1 mile (Wind, Challenging)
Sprint 1 mile (Wind, Strenuous)
Stroll 10 miles (Stamina, Relaxing)
Hike 10 miles (Stamina, Challenging)
March 10 miles (Stamina, Strenuous)
Trek 100 miles (Health, varies)
Friendly Competition Example
The fact that more difficult tasks tend to require a player with a constant skill level to focus more carefully on the task in order to have the same likelihood of success means that an easy but intense task will often (in practice) consume the same amount of effort as a difficult but relaxing task. For example, suppose you are a an ordinary intelligent adult who occasionally enjoys playing strategy games on the weekend (Abstract Strategy: 5 ranks). Suppose you are playing a game of chess against your six-year-old nephew. On the one hand, Chess is an inherently Strenuous mental activity. On the other hand, your nephew has no training at chess or, for that matter, at any strategy games more complicated than Uno (skill level: +1), so you can afford to adopt a Casual attitude toward the game, giving you a -4 penalty. Your effective skill will be 5 - 4 = 1, and your nephew's skill will also be 1. You will spend 3 effort for a Casual, Strenuous task, and the game will be enjoyable and evenly matched.
Now, suppose you are playing a game of checkers against your retirement center's local cardsharp (Abstract Strategy: 15 ranks). All this dude does for fun is play bridge and checkers. 15 / 5 = 3. As a "Level Three" strategist, the cardsharp can play three games of checkers against untrained opponents simultaneously and still be likely to win all three games. Although Checkers is an inherently Relaxing mental activity, you are somewhat outclassed, and so you adopt an Intense attitude toward the game to try to compensate for your lower skill. In a one-on-one match, you would have a skill level of 5 + 4 = 9, and your opponent would have a skill level of 15. Even trying hard, you would have to get pretty lucky to win (the cardsharp should expect to win roughly 74% of your games). During each game, you will spend 3 effort for an Intense, Relaxing task.
Note that if you play checkers all day, you will probably get fatigued before the cardsharp does. The cardsharp can afford to spend only 1 or 2 effort per game (even with a -4 penalty, making the skill comparison +11 to +9, the cardsharp would win 57% of the games), whereas you must spend 3 effort each game just to have a fighting chance at pulling off an upset victory. A typical game of checkers would drain Focus, so after 7 games or so, you will probably be down to 30% or 40% Focus, and will thus suffer a further -2 or -3 fatigue penalty, whereas the cardsharp will probably still have about 60% of his Focus Pool left and will thus only suffer a -1 fatigue penalty. This additional advantage will allow the cardsharp to stick strictly to a Casual effort and still beat you three times out of four, further conserving the cardsharp's efforts. After twenty games in a row, you will be risking your Sanity and looking at fatigue penalties of -6 or -7 if you try to keep playing, whereas the cardsharp will have several points of Focus left and suffer only a -3 fatigue penalty.
On the other hand, if you bring two friends with you and force the cardsharp to play a simultaneous exhibition match, you should be able to wear the old man down -- true, you and your friends spend 3 Effort per person per game, but the cardsharp has to spend 1.5 effort per opponent per game to be assured of victory, or 4.5 effort per round. Thus, after 5 exhibition matches, you and your friends will have roughly half your focus left, suffering Fatigue Penalties of -2, whereas the cardsharp will have spent 1.5 * 3 * 5 = 45 Focus, and will likely running significantly into his Sanity Pool, suffering a Fatigue Penalty of -6 or so. At that point, a typical cardsharp would drop to a purely Casual effort to avoid suffering serious sanity penalties (most people don't literally play games until it drives them insane). Although the cardsharp would have won roughly 9 of the first 15 games, he would probably *lose* 9 of the next 15 games. Your team has a skill of 5 (base skill) + 4 (intense effort) - 2 (fatigue penalty) =+7, whereas the cardsharp has a skill of 15 (base skill) - 4 (casual effort) - 6 (fatigue penalty) = +5.
Deadly Combat Example
Suppose two evenly matched amateur swordfighters (Sabers: 10 ranks) are duking it out, ostensibly to the death, over a broad, uncluttered dry prairie. Call the marginally quicker swordfighter Tim, and the marginally slower one Wulfred. Tim opens the combat by choosing the strategy "Probe" and the attitude "Ordinary." Swordfighting is an inherently strenuous activity of short duration, so an ordinary attack would usually cost 5 Wind effort. However, the Probe Strategy reduces the damage dealt on a successful attack by -6 in exchange for reducing the effort cost by -1 (to a minimum of 1; effort costs can never be reduced to 0 or below). Thus, Tim will spend 4 Effort.
Wulfred chooses to defend using the Parry strategy -- he will attempt to batter his opponent's sword away by hitting it sharply and quickly. Knowing that a Probe attack will not be especially damaging, Wulfred puts forth a Casual effort, accepting a -4 penalty to his chance of success. A Casual, Strenuous activity usually costs 3 effort. However, the Parry strategy costs 1 additional effort. In exchange, if successful, it leaves the opponent Unready for one additional turn. Thus, Wulfred will spend 3 + 1 = 4 effort.
After both players have chosen their strategies for the tick, they each roll and resolve combat. Tim rolls a 12. Making a Probe attack with a saber has a difficulty of 15 -- it is not easy for an untrained person, but it is not especially difficult, either. With 10 ranks in Saber, Tim scores a 10 + 12 = 22, so his saber attack will be brought off with proper form, and Wulfred needs to defend. Making a Parry defense with a saber has a difficulty of 18 -- an untrained person will usually not manage to get the sword into place in time, but parrying is still a basic move, so even an amateur fencer can usually pull it off without too much trouble. Wulfred rolls a 9 on his defense, which would usually be enough to successfully parry: 10 + 9 = 19, which is more than the difficulty of 18. However, because Wulfred made only a Casual effort, he suffers a -4 penalty, and must so his adjusted skill roll is 19 - 4 = 15, which is less than 18. Wulfred could spend 3 suckage points to avoid failure by, e.g., damaging his bracers (1 point) and falling to one knee (2 points), but decides not to bother. Instead, Wulfred allows the attack to pass the 'first threshold,' making a 'flailing defense.' He rolls 4d6 to determine the effort cost (Wind) of his defense, taking 1 Stamina damage for each "6" that shows on the dice. He rolls [1, 6, 2, 4] for a total of 13 Wind spent and 1 Stamina spent (from strained muscles, e.g.). This 13 Wind is in addition to the 4 Wind Wulfred spent to initiate the defense.
Thus, assuming standard-sized fatigue pools at the end of the first tick of combat, Tim has 30 - 4 = 26 Wind remaining and a full 30 points of Stamina remaining, whereas Wulfred has 30 - 4 - 13 = 13 points of Wind remaining and 30 - 1 = 29 points of Stamina remaining. Neither player is Ready to attack -- a Probe attack makes players unready for one turn, and a flailing defense makes players unready for two ticks. On the next tick, both players rest while keeping their swords in a loose en garde position -- Tim converts 1 point of Stamina into 4 points of Wind, leaving him at 30/29/40, and Wulfred does the same, leaving him at 17/28/40. Tim currently suffers no fatigue penalties. Wulfred is down to a half-pool of Wind, giving him a -2 fatigue penalty.
On the third tick, Tim is ready to attack again, and chooses to launch a full-blown Swing attack as his strategy. Waiting another tick would give Wulfred a chance to recover without benefiting Tim. Feeling overconfident after his initial success, Tim uses only a Casual attitude, and spends 3 effort for a Casual, Strenuous activity, plus 2 additional effort for his strategy, for an initial total of 5 Wind spent on the attack. A Swing attack costs +2 effort, but, if successful, has a good chance (25%) of damaging armor. Wulfred again chooses to defend by Parrying, but this time chooses to make an Intense effort. An Intense, Strenuous activity costs 8 effort, plus 1 effort for the Parry strategy, for a total of 9 Wind spent. Note that effort spent during a tick does not factor into the fatigue penalty for that tick; fatigue penalties are only adjusted between ticks.
Swinging a sword has a difficulty of 12; pretty much anyone can take a good swing with a stick, although swords are heavy. Tim rolls an 6 on his attack. 6 (roll) + 10 (skill) - 4 (attitude penalty) = 12, which is exactly equal to the difficulty of swinging. That's good enough, though, so the attack goes through. Wulfred rolls an 8 on his defense. 8 (roll) + 10 (skill) + 4 (attitude bonus) - 2 (fatigue penalty) - 1 (unreadiness defense penalty) = 19, which is better than the required parrying difficulty of 18. Wulfred's defense succeeds, causing the Parrying bonus of one additional turn of unreadiness to kick in. Tim will be Unready for the next two ticks anyway because of his Swing attack, so the successful Parry means that Tim will be Unready for the next three turns. A successful parry carries no unreadiness penalty, and the unreadiness from the flailing defense has expired, so Wulfred will be Ready at the start of the fourth tick.
At the start of the fourth tick, Tim has 25/29/40, and Wulfred has 8/28/40. Tim is Unready for the next three ticks, whereas Wulfred is Ready. Tim is suffering no fatigue penalties, but Wulfred is suffering -3 for being down to the last quarter of his Wind pool. Thus, Wulfred chooses to wait one toick before attacking. Both players rest; Tim is now at 29/28/40, and Wulfred is at 12/27/40. Wulfred's fatigue penalty is now back at -2; Wulfred is Ready and Tim is Unready for the next two turns. Wulfred would like to rest again, but Tim decides to attack early, even though he is unready!
Tim chooses a Feinting attack -- a strategy that reduces damage dealt on this tick by -4, but, if successful, makes the defender's next defense roll suffer a -6 difficulty penalty. Tim uses Ordinary effort. Wulfred puts forth a Casual effort behind his strategy of Block -- a standard attempt to absorb the force of the blow on one's blade that carries no modifiers. Wulfred will spend 3 Wind effort for a short, casual, strenuous task. Tim will spend 5 Wind effort for a short, ordinary, strenuous task. Tim will also spend 2 Wit to enable his strategy, although he is unlikely to run out of Wit any time soon, so that will not be tracked in this example. Finally, Tim spends an additional 5 Wind for breaking the rule against attacking while Unready. Feinting is a challenging trick move that has a difficulty of 20; Blocking is a standard, ordinary move with a difficulty of 10.
Tim rolls a natural 1 - it's a pretty terrible attempt at a Feint that even a child could see right through. 1 (roll) + 10 (skill) - 5 (attack unreadiness penalty) = 6. 6 fails the difficulty level of 20 by 10 points or more, so Tim must roll against the chance of an accident. Fatigue penalties are only adjusted between ticks, so Tim gets to roll the full d20, with no fatigue penalty. He rolls an 8, meaning that he suffers a minor accident. The DM rules that Tim stumbles, spending 2 Wind, and dents his boots while trying to recover his balance after the failed feint. The dented boots will not have any immediate effect on combat, although a character might notice that the boots are dented if, e.g., they come across the suit of armor while it is hanging up on display. Repeated minor accidents might eventually wear a hole in the boots, providing a penalty against speed. Because TIm's roll fails, Wulfred is not required to make a roll to defend, and Wulfred spends only half of his usual defense effort (round down, to a minimum of 1).
Tim's total Wind spend is 5 + 5 + 2 = 12, bringing him down to 13/29/40. Wulfred's total Wind spend is (3/2) = 1, bringing him down to 11/27/40. Tim will be Unready for 1 more turn, with a fatigue penalty of -2, and Wulfred is Ready, with a fatigue penalty of -2. With the heat of battle roaring in their ears, Wulfred starts the fifth tick by launching an Intense Swing, spending 8 + 2 = 10 Wind, and Tim defends with an Intense Parry, spending 8 + 1 = 9 Wind. Wulfred rolls a 15, scoring 15 (roll) + 10 (skill) + 4 (attitude bonus) - 2 (fatigue penalty) = 27, which is plenty for a Swing. Tim rolls a 4, scoring 4 (roll) + 10 (skill) + 4 (attitude bonus) - 2 (fatigue penalty) = 16, which is not quite enough for a successful Parry. Note that what's driving the result here is not so much the massive 27 attack as the fact that 16 is too low of a number for a successful Parry. If both sides were not fatigued, the results would have been 29 and 18; 18 would have successfully defended against 29.
Tim chooses to use suckage points to avoid passing the first threshold -- he drops to one knee to cushion the force of the swinging blow, which is worth 2 suckage points. 16 + 2 = 18, so he avoids the extra penalty from the Swing…but he does not get the bonus result from the Parry, which must succeed unaided to have an effect. Tim is now Ready, although his awkward one-knee position may not be great for launching attacks. After his Swing, Wulfred will be Unready for the next two ticks. Tim has 4/29/40; Wulfred has 1/27/40. Both characters now suffer a -3 fatigue penalty, because three-quarters of their Wind pools are empty.
On the sixth tick, Tim gets back up into a standing position, spending 1 Wind to do so in his light armor (getting up from one knee is not very strenuous, and Tim is good enough at it to succeed automatically even with a casual effort). Tim is now at 3/29/40; Wulfred rests, going up to 5/26/40. Both players still have fatigue of -3.
On the seventh tick, one or both players will likely attack, further increasing fatigue. Even if both players rested, the drain on Stamina is starting to get to the three-quarters mark, so measurable fatigue will start to kick in that way if the players duel for more than a dozen or so ticks. As fatigue increases, serious injuries become more likely, both because defense rolls will be lower relative to the rolls needed for success, and because accident rolls suffer an inherent penalty from fatigue, and because armor will tend to degrade as combat goes on, increasing the damage dealt by a successful hit. Although amateur evenly matched sword fighters can duel for several ticks without real risk of serious injury (even when rolls were low, like "1" or "4," nothing really bad happened), eventually one or both players will be forced to stop fighting or risk bloodshed.
Mechanical Assembly Example
Suppose you are trying to assemble a radio, despite having only a passing familiarity with the theory and practice of electronics (Electronic Engineering: 5 ranks). Assembling a radio from spare parts is challenging -- probably a DC 20. If you had no idea what a transistor looked like or how it worked, the odds of assembling a radio from unlabeled pieces is essentially zero, but if you know a little bit about what you're doing, you might manage it in only a few tries.
In terms of intensity, radio-assembly is probably Challenging…it's not the kind of thing you can do without even looking at what you're doing, but you probably could fairly easily carry on a conversation while you worked without significantly affecting your odds of success. In terms of duration, it probably takes a couple of hours to build a radio if you're working from parts rather than a ready-to-assemble kit, so you would spend Focus points. A well-labeled kit might use Wit points or even be Relaxing instead of Challenging, although it would still have a respectable difficulty -- perhaps DC 13.
So, each time you attempt to assemble a radio in your garage, assuming an Ordinary effort, you spend 3 Focus points -- the default effort spend for an Ordinary, Challenging activity. You then roll a d20. If it comes up 15 or better, you succeed! You build the radio. Thus, you have a 1 in 4 chance of getting it right on the first try. If the roll comes up between 6 and 14, your radio doesn't work, but nothing else goes wrong. A couple of hours go by, and you spend 3 Focus, and you can try again if you want to. If you're really short on spare parts, you might have to roll to disassemble the radio before you can roll to re-assemble it. Otherwise you could just set the broken radio aside and try to build a second radio from new parts. If the roll comes up 1, 2, 3, 4, or 5, though, then you have an accident.
Exactly how bad the accident is depends on your luck, and your fatigue levels. If you started out totally fresh, your odds are very good -- you have a 20% chance of a moderate accident, a 30% chance of a minor accident, and a 50% chance of no accident. Barring unusual circumstances, minor accidents will only cost you a couple of points of effort -- maybe you smack your arm against the cabinet while trying to catch a part that you dropped, costing you 3 Wind or 1 Stamina. Moderate accidents can get in the way by creating environmental hazards that give you penalties to further attempts. If, e.g., you spill battery acid on your garage floor, you would have to either clean it up (requiring a skill roll for toxic cleanup), move somewhere else (possibly spending Wind to do so) or get a semi-permanent -1 penalty to your assembly skill level for having to tiptoe around the acid while you work.
On the other hand, suppose you started out somewhat fatigued from 8 hours at your day job (Focus drain: 12 points) and then got unlucky on your first three attempts to build the radio, costing you another 9 Focus. Now you're down to 30 - 12 - 9 = 9 Focus, or one-quarter of your tank, so you get a -3 fatigue penalty.
Your fourth attempt will have a higher chance of an accident -- a roll of 1, 2, 3, 4, 5, 6, 7, or 8 will mean an accident roll. Once you do roll for an accident, things are more likely to go wrong -- you have a 15% chance of a major accident, a 20% chance of a moderate accident, a 30% chance of a minor accident, and a 35% chance of no accident. Basically, you are tired enough that you should expect something to go wrong about half the time if you wearily set yourself to the task of building yet another radio at, e.g., 10 pm. You could reduce this risk by using an Intense effort, giving you a +4 bonus -- but that would cost you additional Focus, and it would still not guarantee that you succeed in building the radio. On a roll of 12, for example, 12 (roll) + 5 (skill) + 4 (attitude bonus) - 3 (fatigue penalty) = 18, which is short of the 20 needed to assemble the radio. At that point, it might make sense to spend 2 suckage points to take twice the time and twice the parts to finish a working radio at 2 am, rather than to wind up with yet another broken radio at midnight and then try again with a fatigue penalty of -4.
Of course, usually things go better than this -- but you never know, and that's why, when you set yourself a non-trivial task, you have to roll. If you don't need the radio urgently, you can always cook dinner or even go to sleep after the first couple of attempts, and try again (with a much more comfortable fatigue penalty) when you're freshly rested. This is probably why, in real life, most hobbyists build their radios on the weekends.