Operations as defined by the Annulus ruleset includes anything that adventurers do to manipulate, analyze, investigate or reform mechanisms, objects, structures or scenes to achieve a desired result. This includes but isn't necessarily limited to activities such as:

• Picking a lock.
• Hacking into a database.
• Disabling a mechanical trap.
• Patching up a wounded companion.
• Picking up the trail of a fugitive.
• Forging official documents.
• Sabotaging a wagon wheel.
• Jamming a door shut.
• Hotwiring a motorcycle.
• Fixing an engine.
• Checking a crime scene for clues.
• Drawing a magic circle.
• Building a raft from driftwood and junk.
• Unclogging a toilet.
• Performing surgery.
• Escaping from confinement.
• Removing a key from around the neck of a sleeping ogre.
• Making a decent copy of the writings in a ruin.
• Reforging a sword of legend.

All operation activities use the same method to resolve success or failure and are known as Operation Challenges.

There are four different difficulties of operation challenge: easy, medium, hard, and impossible. The difficulty of a challenge determines the number of successes required to be effective with all checks applied to the challenge. Easy challenges require two successes, medium challenges require three, hard challenges require four and impossible challenges require five. The GM announces the difficulty of a given challenge when setting it up.

Interacting with a given operation challenge requires a check from each individual participant with a number of successes equal to the normal difficulty of the challenge. This check takes one disadvantage per individual that is already working on the challenge. If an entry check is failed, it cannot be re-attempted and the individual making the check cannot meaningfully help with the challenge in question.

For example, say the adventurers Sarah and Dimitri are attempting to find incriminating documents in the mayor's office. The GM decides this is a Medium-difficulty challenge, thus all checks relating to it require three successes to be effective. Sarah makes a check to enter the challenge and gets four successes- more than enough to participate in the challenge. Dimitri attempts to also join the challenge, but rolls his check with a disadvantage due to there already being one person working on the challenge (Sarah, who just joined.) Dimitri gets only two successes, meaning he can't help this time- the filing system really confuses him or something. If both adventurers had failed to enter the challenge, then they would have automatically failed to find the evidence they were after and would now have to come up with an alternate plan.

To set up an operation challenge, the GM rolls six of 12-sided dice and places them in a line in the order they were rolled. For example, if the GM rolled a 7, 9, 7, 3, 11, and 5 they would line them up like this (assuming no dice start hidden, see Hidden Dice below for an explanation):

[7][9][7][3][11][5]

The goal of a tinkering challenge is to make it so every die in the challenge is exactly one number different from every die it neighbors. For example, a sequence of [1][2][3] is a valid solution, as is [3][2][1] and [1][2][1]. If for some reason an operation challenge has only one die, then it is automatically considered solved no matter what number is displayed on said die.

Sometimes not all the parts of an operation are immediately apparent. When the GM rolls the six 12-sided dice for a challenge, they first secretly roll six six-sided dice in a line in the order that they are rolled where none of the players can see. These six-sided dice correspond to the player-visible twelve-sided dice. Any of the six-sided dice that display a result of 1, however, are considered “hidden”. The GM does not roll a corresponding 12-sided die for any of their six-sided dice that display a 1.

For example, say the GM secretly rolls their six-sided dice and get the following results:

[5][3][4][3][1][2]

The presence of a 1 means that one of the dice in the challenge is hidden, so the GM rolls five 12-sided dice in plain view of the players. The players solve the current challenge as-is, but then upon “solving” the puzzle, the hidden die is revealed and inserted into the die chain in the appropriate location. If there are multiple hidden dice, only one is revealed at a time and only when all visible dice are “solved”. Hidden dice are revealed in order from left to right (the GM might have to point out which end of the chain they are revealing hidden dice from).

In the above example of [7][9][7], the three numbers are not a valid sequence since the [9] is 2 points different from both of the [7]s beside it. Fortunately, any creature that has successfully joined the operation can use a minor action to attempt to change one of the dice to a number 1 higher or lower.

A creature could therefore change the above example into this:

[7][8][7]

with just one action, making that part of the sequence already “solved” and allowing them to turn their attention to the rest of it. Adjustments are not guaranteed to succeed, however- sometimes they result in a jam instead of the desired number change (see below).

Every time a creature makes an adjustment on any die in an operation chain, they must first roll a check to see if they screwed something up or otherwise made things more difficult for themselves. This is a standard four-die check and requires a number of successes dependent on the difficulty of the challenge. If the check fails, the die jams and its number is not changed.

When a die “jams” it becomes stuck on whatever number it currently displays. It is suggested that the die be marked in some way to visually represent its jammed status- one simple way is to simply turn it so that the number it displays is upside-down in comparison to the other dice (this doesn't work if your dice read the same in either orientation), or physically move it slightly out of the line that the others are in.

A jammed die cannot be manipulated any further in any way. If dice are jammed in such a way that solving the operation challenge is impossible (such as by having two adjacent dice with numbers more than 1 point apart both jam) then the operation challenge fails.

Knacks are special abilities your adventurer can use to make overcoming operation challenges easier. See the Knacks page for more details. More difficult challenges will almost necessitate the use of knacks.

Knacks require a check to use. If a knack is attempted but the check fails, then that knack becomes unavailable for use for the remainder of the challenge but the challenge is otherwise unaffected by the knack's failure.

As a review, this is the basic sequence of events for a tinker challenge:

1. GM secretly rolls as many six-sided dice as the challenge calls for and lines them up.
2. GM then rolls a number of 12-sided dice corresponding to the number of six-sided dice that are not displaying a result of 1 and lines them up for the players.
3. Player points to a die and declares what they wish to do to it (such as “change this 4 to a 5.”) This costs the player one action.
4. Player rolls for jamming. If the result is not a jam, their declared plan of action is carried out.
5. If the result is a jam, the die they were pointing to immediately jams on its current number and its displayed number is not changed in any way from before they made their declaration.
6. Player continues until either finishing the challenge or enough dice are jammed in such a way as to make that impossible.
7. If the challenge is finished with no hidden dice, the players achieve their objective. If not, a single hidden die is revealed and inserted into the chain in the appropriate location.