The basis of all mechanics on the game comes down to deciding which action a character is taking and how difficult the task is.

Open D6, as implied in its name, only uses six-sided dice.

A player determines all such values for a character in chargen.

During play, for any possible action at which a character could fail, the Story Teller or Plot Runner in that moment determines how hard a given task is and sets a difficulty number (DN) for the task or challenge. They then decide which skill is most appropriate to the task.

The Character's player then rolls the dice indicated on their sheet under that skill. If they do not have the skill, they instead roll its base attribute. Note that on the game, a character only has to +roll <skill name>; if they do not have it, the game will default to the attribute and roll that. The total sum of all dice are then compared to the DN and if the roll was higher, the character has succeeded at that task.

Generic Difficulty Numbers

Level Number
Automatic 0
Very Easy 1–5
Easy 6–10
Moderate 11–15
Difficult 16–20
Very Difficult 21–25
Heroic 26–30
Legendary 31 or more

Setting Difficulty Numbers

Sometimes its easier to consider the number of dice rolled along with their average result to know where a character is skill wise and how difficult to make some challenges.

Here is a quick chart to show how many dice (not including the pips) will succeed on average (only on average) against one of the basic steps above.

Level Dice on Average
Very Easy @ 5 DN 2d6
Easy @ 10 DN 3d6
Moderate @ 15 DN 4D6+2
Difficult @ 20 DN 6D6
Very Difficult @ 25 DN 7D6+1
Heroic @ 30 DN 9d6
Legendary @ 35 DN 10D6

This is on average, just under half the time the above dice will fail at those levels.

Preparing or Rushing actions

Outside of fast paced rounds, a character may be in a situation that allows more or less time to complete a standard action, such as researching knowledge skills in a library.

If a character can double the time of the standard action, they can +1D per doubling up to +3D.

Example: The characters need to look up history on Neptune, there is no rush. Normally a characrter might flip through a book or online and spend an hour to find the info they need. Perhaps they decide to spend two hours on this, they would gain +1D to their knowledge check for time preparing alone. If they doubled again to four hours in the library, +2D and if they just spent the day (8 hours) researching all they could, then +3D.

Similarly an action may be rushed if necessary. This instead increases the difficulty; by +5 if rushed by 25% time, +10 for 50% time reduction, and +20 for 75% time reduction. No one may reduce the time beyond 75%.

Example: A doctor is conducting an hour long surgery, but is now rushed do to a bomb in the vicinity. They decide to try to complete it in 30 minutes to get out of the building in time. The difficulty number is increased by +10 for this reduction in time.


When time is reduced to rounds (~6 seconds or so), sometimes a character needs to perform more than one action. Defend and cut the wires, run and take cover, run while laying down fire at the enemy to not be a sitting duck and try to dodge a little. Whatever the case may be, for each action beyond the first intended, all dice rolls for their turn suffer -1D per extra action.

Relative Skills and Assisting Others

When given time to perform an action, sometimes two or more skills may apply to the same action. When multiple skills apply and there is time to use them, the Storyteller or Plot Runner will determine the primary action that is being performed and what other skills may be beneficiary to the action.

Each relative skill is rolled against the DN, and the DN is subtracted from the result. All such are rolled and accumulated, net positive or negative. The final is divided by too and applied to the primary skill (the number can reduce this roll on failed relative skill rolls).

Similar to this, is Assisting Others. One character may attempt to assist the primary character, by rolling their own skill against the DN. Again, the DN is subtracted from the result and the result, positive or negative is applied to the primary character's rolld.

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