334 Cepheus — Part 1: Core Mechanics
Design Philosophy
334 Cepheus is built on a simple truth: competence should feel reliable, but never safe. The universe is dangerous because the situations are dangerous—not because the dice hate you. These rules preserve the classic 2D6 engine while removing punitive randomness, flattening modifier inflation, and giving players meaningful choices at every roll.
The Core Roll
When the outcome of an action is uncertain, the player rolls two six-sided dice (2D6) and adds all applicable modifiers.
2D6 + Modifiers ≥ Target Number
The default Target Number (TN) is 8.
Modifiers come from:
- Characteristic Modifier (DM)
- Skill Level
- Situational circumstances
- Difficulty (set by the Referee)
Modifiers are cumulative, but the total modifier is capped at ±4. Any modifier beyond that becomes Boon or Bane dice (see below).
Characteristics
Every character has six characteristics, each rated from 1 to 15. Generate them by rolling 2D6+6 in order, then you may swap any two.
| Characteristic | Abbreviation | Measures |
|---|---|---|
| Strength | STR | Muscle, lifting, melee damage |
| Dexterity | DEX | Reflexes, coordination, initiative |
| Endurance | END | Stamina, health, resistance |
| Intelligence | INT | Reasoning, memory, perception |
| Education | EDU | Formal learning, technical knowledge |
| Social Standing | SOC | Status, influence, connections |
Characteristic Modifiers
| Score | 1–2 | 3–5 | 6–8 | 9–11 | 12–14 | 15 |
|---|---|---|---|---|---|---|
| DM | −2 | −1 | +0 | +1 | +2 | +3 |
Difficulty
The Referee sets the Difficulty before the roll. The player does not apply a Difficulty modifier to their roll. Instead, the Difficulty shifts the Target Number.
| Difficulty | Target Number | Approx. Success (no modifiers) |
|---|---|---|
| Simple | 4+ | 92% |
| Routine | 6+ | 72% |
| Standard | 8+ | 28% |
| Difficult | 10+ | 8% |
| Very Difficult | 11+ | 3% |
| Formidable | 13+ | <1% |
Rule of thumb: If a competent professional (Skill-1, DM +1) should succeed most of the time, the task is Standard (8+). If they should struggle, it is Difficult (10+).
Boon and Bane
When circumstances, equipment, or preparation would push a modifier beyond the ±4 cap, or when the Referee wants to represent exceptional advantage or disadvantage without altering the math, use Boon and Bane dice.
- Boon: Roll 3D6 and keep the highest two.
- Bane: Roll 3D6 and keep the lowest two.
Boon and Bane are binary —you either have the advantage or you don't. They do not stack. If you have both, they cancel out.
Sources of Boon: Superior equipment, extensive preparation, attacking from higher ground, acting with surprise, relevant prior knowledge. Sources of Bane: Poor equipment, exhaustion, acting under fire, unfamiliar technology, severe distraction.
Effect and Degrees of Success
The margin by which you succeed or fail is called Effect.
Effect = (2D6 + total modifiers) − Target Number
Always narrate the degree. Do not report only pass or fail. Tie a mechanical benefit to the band, using this table.
| Effect | Degree of Success | Narrative & Mechanical Impact |
|---|---|---|
| −6 or less | Exceptional Failure | Disaster. Equipment breaks, you are exposed, or an ally suffers. The attempt creates a new problem. |
| −5 to −2 | Failure | You fail. No progress, and the time is spent. |
| −1 | Marginal Failure | You fail. The Referee may offer success at a serious cost; you may refuse and simply fail. |
| 0 to 2 | Marginal Success | Bare success (the 1–2 band, including a total that only equals the TN). It takes longer, makes noise, or leaves evidence. No bonus information. |
| 3 to 5 | Success | Clean success, on time, with no complication. If the task has a duration, it finishes one step sooner. |
| 6+ | Exceptional Success | Clean success, plus one tangible benefit: +1D6 damage on an attack, the time cut in half, or one bonus fact the other party did not mean to reveal. |
Unskilled Tasks
If you attempt a task for which you have no skill, you suffer a −1 DM (not −3). This represents the fact that basic education and common sense go a long way.
If the task involves alien technology, advanced physics, or military-grade encryption, the Referee may increase the penalty to −3 DM or raise the Difficulty by one step.
Opposed Tasks
When two active opponents clash, both roll. The higher Effect wins.
- Tie: The defender wins, or the situation remains unresolved.
- Exceptional Success (6+): The winner may choose to inflict an additional consequence on the loser (disarm, pin, expose a flank, etc.).
Common opposed tasks: Stealth vs. Recon, Deception vs. Insight, Hacking vs. Computer Security, Grappling.
Extended Tasks
Some tasks cannot be resolved in a single roll. Researching an alien artifact, repairing a jump drive, or negotiating a trade agreement may require multiple successful rolls over time.
The Referee sets:
- Target Successes: Typically 3–6.
- Interval: How long each attempt takes (1 hour, 1 day, 1 week).
- Complication Threshold: If a roll results in Exceptional Failure (−6+), the task cannot proceed until the complication is resolved.
Each successful roll accumulates one success. The task is complete when the target is reached.
Critical Outcomes
On any roll of natural 12 (double sixes), the result is a Critical Success —treat Effect as if it were at least +6, regardless of modifiers.
On any roll of natural 2 (snake eyes), the result is a Critical Failure —treat Effect as if it were at least −6, regardless of modifiers.
These override normal math. Even a heavily penalized roll can crit-succeed on double sixes. Even a guaranteed success can crit-fail on snake eyes.
Quick Reference: Making a Roll
- Referee declares the Difficulty → sets the TN.
- Player declares the relevant skill and characteristic.
- Total the modifiers: Characteristic DM + Skill Level + Situational DMs (max ±4).
- Check for Boon or Bane.
- Roll 2D6 (or 3D6 keep two).
- Add modifiers. Compare to TN.
- Calculate Effect. Narrate the degree of success.
Example in Play
Mira is trying to hack a corporate security door. She has INT +1, Computers-2, and a decryption kit (+1 DM). The Referee calls it Difficult (TN 10) because the system is military-grade.
Total modifier: +1 (INT) + 2 (skill) + 1 (kit) = +4 (at cap). No Boon.
Mira rolls 2D6 = 7. Total: 7 + 4 = 11. Effect = 11 − 10 = +1.
Marginal Success. The door opens, but the system logs an anomaly. Security will investigate in 1D6 minutes.
If she had rolled 10, total would be 14, Effect +4 (Success)—the door opens cleanly, no trace.
If she had rolled 12 (natural), that's a Critical Success. Effect becomes +6 (Exceptional). She not only opens the door but discovers a backdoor into the building's camera network.