Four D Two System
Four D Two, FourDTwo, 4D2 are wordplays on 42.
The answer to the wrong question.
4D2 Mechanic
4D2 is both a descriptor and a joke. The 4 indicates that the Mechanic uses 4 dice. The 4 also indicates that there are 4 steps in the process. The D refers to dice, as in the "D" in the 4d6 convention. The 2 reflects that the Mechanic has two directions. The joke is that 4D2 sounds like 42. FortyTwo is the answer to the question. The 4D2 Mechanic gives the answers to questions you don’t understand.
The 4D2 Mechanic uses four sixsided dice to guide the story in the Role Playing System. The 4D2 Mechanic is a bespoke decision tool for EXP’s RolePlaying System. 4D2 replaces Attack Rolls, Performance Rolls, Attribute Rolls, Saving Rolls, Sphincter Rolls and more.
In the RolePlaying System, the 4D2 Mechanic is used to guide the story. Players ultimately guide the results generated by the 4D2 Mechanic.

Get a Number from the die roll

Get an Outcome from the Number

Get a Descriptor from the Outcome

Continue the Story
Number
A player generates a number by rolling two pairs of competing six siders. The player rolls 2d6, generating a number between 2 and 12. The player rolls 2d6 again, generating another number between 2 and 12. The player subtracts the second roll from the first roll. The sum of these two numbers generates the Number of the 4D2 Mechanic.
How to Roll Dice
The more dice rolled at once, the more efficient the mechanism. The player first rolls two six siders (2d6). The first roll is the positive value. The same player rolls another two six siders (2d6). The second roll is the negative value. Some quick arithmetic generates the Number.
The player can roll all four dice at once to save time. One pair of dice generates the positive roll. A different coloured pair of dice generates the negative roll. For example, the positive six siders could be green, and the negative six siders could be red.
(6+1)  (4+2) = +1
The player can generate the number by rolling one six sider four times. Rolling this way makes the process more dramatic and more timeconsuming. Ultimately players and playgroups will develop their style for generating 4D2 mechanic Numbers.
Example Rolls
The player rolls 2d6, and the sum is 12. She rolls another 2d6, and the sum is 2. The 4D2 Mechanic Number is +10 (12  2). +10 is the best number possible for the player’s persona.
The player rolls 4d6 all at once. Her red dice are positive, and the sum is 9. Her white dice are negative, and the sum is 8. The 4D2 Mechanic Number is +1 (9  8). +1 is a typical number and represents a slight win for the persona.
The player rolls 1d6 four times in a row. Her first roll is 3. Her second roll is 1. These two rolls generate a positive roll of +4. Her third roll is 4. This roll is subtracted from +4 to get 0. Her fourth roll is 6. This roll is subtracted from 0 to get 6. The 4D2 Mechanic Number is 6. This number is terrible, and badness is coming for the player’s persona.
Outcome
The outcome translates the number into a colourful account of the die roll. The 4D2 Mechanic Number transforms into an Outcome for fun and efficiency.
The 4D2 Mechanic Number can be used as a raw number to determine what happens to the persona. Everyone at the table is aware that +10 is great and 10 is a disaster. What do all those other Numbers mean? Each Number result has an Outcome associated with it. There is an Outcome table that has correspondingly dramatic Outcomes for each Number.
For example, +10 is an Immaculate Success, and 10 is a Cataclysmic Failure.
4D2 Roll → Number → Outcomes.  

Number 
Outcome 
+10 
Immaculate Success 
+9 
Wondrous Success 
+8 
Magnificent Success 
+7 
Majestic Success 
+6 
Masterful Success 
+5 
Extraordinary Success 
+4 
Outstanding Success 
+3 
Superior Success 
+2 
Solid Success 
+1 
Barely Successful 
0 
Detent 
1 
Minor Failure 
2 
Clear Failure 
3 
Major Failure 
4 
Severe Failure 
5 
Massive Failure 
6 
Complete Failure 
7 
Grievous Failure 
8 
Disastrous Failure 
9 
Calamitous Failure 
10 
Cataclysmic Failure 
Number 
Outcome 
The Outcome Table helps guide the players describe the Outcome of the maneuver. A positive Number yields a good Outcome. A negative Number yields a bad Outcome. The Outcome may be all the players need to move the story along. For example, a veterinarian is removing a splinter from a feline’s paw. An Outcome that is an Immaculate Success would be enough to guide a happy story.
Example Outcomes
The number +10 is an Immaculate Success. This Outcome is rare. Immaculate success represents the best possible Outcome for the persona. The player can choose to kill, wound, or incapacitate her opponent. A persona’s maneuver would be very successful, leading to unexpected benefits.
The number +2 is a Solid Success. This Outcome is quite common. Solid success represents a positive outcome for the persona, but nothing dramatic. In combat, the persona has won an advantage, but the combat story is undecided. A repair maneuver was successful but may fail sooner than expected.
The number of 10 is a Cataclysmic Failure. This Outcome is rare. Cataclysmic failure represents the worst possible Outcome for the persona. In combat, the persona will suffer total defeat. The persona could die or be lethally wounded. Instead of a successful surgery, the patient can die, and the persona loses confidence.
The number 0 is detent. This Outcome is the most common. Detent represents a balance between the positive and negative. The struggle is ongoing. Dramatic fight music continues, and neither persona has the upper claw.
The Outcome may be enough to move the story along. 
Descriptor
Often the Outcome gives enough info for the players to tell the story. The description of the outcome is easy for Immaculate Success and Cataclysmic Failure. For the other 19 Outcomes, the players may need some help.
For recurring 4D2 Mechanic decisions, there are Descriptor Tables. Descriptor Tables give examples of what could happen according to the Outcome. Concrete descriptors are critical when a persona’s life is on the line.
The Descriptor can come from the players or a table. 
There are only two Descriptor Tables included in the Role Playing System. There is a Descriptor Table for Combat and a Descriptor Table for Maneuvers. The players may never need or use either of these tables. Players can use the Descriptor Tables to save time for repetitive acts. The referee and players can create their own Descriptor Tables as they see fit.
Combat Descriptor Table
Below is an example descriptor table for combat outcomes. For details and examples of this table jump to Theatrical Combat.
4D2 roll → Number → Outcome → Descriptor  

Descriptors for combat 

Number 
Outcome 
Organic 
Inorganic 
+10 
Immaculate Success 
Fatal Wound 
Attribute Loss x 2 
+9 
Wondrous Success 
Fatal Wound 
Attribute Loss x 1 
+8 
Magnificent Success 
Mortal Wound 
Attribute Damage 
+7 
Majestic Success 
Mortal Wound 
Peripheral Destruction 
+6 
Masterful Success 
Severe Wound 
Programme Destruction 
+5 
Extraordinary Success 
Wound 
Peripheral Damage 
+4 
Outstanding Success 
Severe Stun 
Programme Damage 
+3 
Superior Success 
Stun 
Severe Rattle 
+2 
Solid Success 
Knockback 
Rattle 
+1 
Barely Success 
Backfoot 
Cosmetic Injury 
0 
Detent 
Ongoing combat story 

1 
Minor Failure 
Nil 
Nil 
2 
Clear Failure 
Backfoot 
Cosmetic Damage 
3 
Major Failure 
Knockback 
Rattle 
4 
Severe Failure 
Stun 
Severe Rattle 
5 
Massive Failure 
Severe Stun 
Programme Damage 
6 
Complete Failure 
Wound 
Peripheral Damage 
7 
Grievous Failure 
Severe Wound 
Programme Destruction 
8 
Disastrous Failure 
Mortal Wound 
Peripheral Destruction 
9 
Calamitous Failure 
Mortal Wound 
Attribute Damage 
10 
Cataclysmic Failure 
Fatal Wound 
Attribute Loss x 1 
Number 
Outcome 
Descriptors for combat 
Maneuver Descriptor Table
Below is an example descriptor table for maneuver outcomes. For details and examples of this table, jump to Theatrical Performance.
4D2 Roll → Number → Outcome → Descriptor  

Number 
Outcome 
Descriptor 
+10 
Immaculate Success 
Invention 
+9 
Wondrous Success 
Enhancement, Permanent 
+8 
Magnificent Success 
Enhancement, Temporary 
+7 
Majestic Success 
Shift for Days 
+6 
Masterful Success 
Shift for Hours 
+5 
Outstanding Success 
Shift for Minutes 
+4 
Extraordinary Success 
Lasts Months 
+3 
Superior Success 
Lasts Weeks 
+2 
Solid Success 
Lasts Days 
+1 
Barely Success 
Lasts Hours 
0 
Detent 
Keep struggling. 
1 
Minor Failure 
Try Again 
2 
Clear Failure 
Wait Minutes 
3 
Major Failure 
Wait Hours 
4 
Severe Failure 
Wait Days 
5 
Massive Failure 
Wait Weeks 
6 
Complete Failure 
Complication 
7 
Grievous Failure 
Severe Complication 
8 
Disastrous Failure 
Damage 
9 
Calamitous Failure 
Severe Damage 
10 
Cataclysmic Failure 
Destruction 
Number 
Outcome 
Descriptors 
Descriptors are cumulative. 
Shifts
Shifts are similar to bonuses or penalties. A shift is anything that moves the Outcome of the 4D2 Mechanism. A Shift of +2 would move a Solid Success (+2) to an Outstanding Success (+4). Shifts are significant and are the only way personas can gain an advantage in the 4D2 system.
Shifts come from the persona’s attributes, abilities and skills. However, anything can become a shift if the players accept it. In handtohand combat, a player could use the PSTR as a shift. When shooting a pistol, the player could use a pistol skill as a shift. A glorious description of throwing a grenade can earn a shift.
Shift Maximums
The maximum number of shifts a player can add to her Outcome is three. The maximum Outcome is +10, which is an Immaculate Success. A roll of 11, 12 or even 13 becomes +10.
Shift Penalties
Shifts cannot be negative. The lowest a player’s shift can become is zero. Penalties can only take away a player’s shift. If a persona wanted to use her DEX as a shift, but her hands were tied, she could not use her DEX shift. However, another persona in the same situation without a DEX attribute would not suffer a 1 shift.
Shifts and Skills
When the player rolls a high number, her persona can gain skills. A high number is one pathway to earning new skills and strengthening the persona. Players cannot use shifts to gain skills. Using shifts to score new skills can lead to rapidly overpowered personas. A +1 shift increases the chance of the persona gaining a new skill three times.
A shift only moves the Outcome and does not change the Number. For example, a player rolls +6 for her number when attacking an enemy. She has three shifts (skill, DEX and a good description). Her number is +6, but her outcome is +9. The persona deals a fatal wound to her target but does not get a random skill.
Example Shifts
A persona is in a pistol shootout. She has pistol skill and DEX attribute. She can Shift her 4D2 Outcome by +2. A Shift of +2 would move a Solid Success (+2) to an Outstanding Success (+4). If her opponent has Pistol 2, then the competing Shifts would cancel out.
A persona is repairing an antigrav modulator on a skimmer bike. She has engine skill one and an INT attribute. The player casts a great yarn about using a piece of wire to reverse the polarity. She can shift her 4D2 Outcome by +3 (skill, attribute, good story). The shift of +3 moves her Minor Failure (1) to a Solid Success (+2).
A persona is play wrestling in the mud pit of a bar. She has no wrestling skills. She can use her PSTR and DEX attributes. She can shift her 4D2 Outcome by +2 (two attributes). The shift of +2 moves her Magnificent Success (+8) to an Immaculate Success (+10). The persona earns the accolades of the bar crowd (Outcome = +10) but does not earn a wrestling skill.
Rules maintain game balance and assist creativity. Do not let rules get in the way of the story or the fun. 
Folded Rolls
A folded 4D2 roll is for when a +/ randomness cannot apply. A persona falling from a great height should not earn a skill from a Wondrous Success. A persona winning a lottery should not have become bankrupt from Catastrophic Failure. These are examples of where the folded roll comes into play. If it is good, how good is it? If it is bad, how bad is it?
To create a folded roll, the player makes a regular 4d2 roll generating a number between +10 and 10. The mechanic would indicate a positive outcome with a positive number and a negative outcome with a negative number. We will avoid any maths here to stay in the spirit of the Role Playing System.
If the 4D2 roll is folding for a positive outcome, all the numbers become positive. The player’s roll now ranges from +10 to +10. The outcome and descriptors remain the same. Only detente and good things can happen.
If the 4D2 roll is folding for a negative outcome, all the numbers become negative. The player’s roll now ranges from 10 to 10. The outcome and descriptors remain the same. Only detente and bad things can happen.
4D2 Mechanic Learning Tools
PDF of Entire Role Playing System
Download a colourful One Pager (177k PDF) here.
Nerdy Curvey Graph
The 4D2 Mechanic generates a smooth curve of numbers between +10 and 10. The Number is playercentric. Positive numbers indicate success, and negative numbers indicate failure. The most common Number from this Mechanic is 0. 0 represents balance, detent or ongoing struggle. +10 represents the epitome of success for the persona. 10 represents the epitome of failure for the persona. The curve is quite beautiful.
Thank you anydice.com