The Star Crusade system is based on the classic Victory Point System from Fading Suns, 2nd Edition, with the incorporation of house rules from our tabletop and online games as well as early drafts of Fading Suns, 3rd Edition and Angus McNicholl's Infinity Engine. The most substantial change is a move from a single-die D20 system to 3D6, creating a more uniform curve.
Basic Task Resolution
On Star Crusade, characters roll a single 3D6, add any appropriate modifiers (the "goal"), and compare it to a target of 20. If they make or beat 20; if they do not, they fail.
The most common goals are based on Characteristic + Skill, plus or minus any modifiers. A test to fire a gun, for instance, is a Dexterity + Shoot roll. A character with a Dexterity of 5 and a Shoot of 5 rolls a D20 and then adds 10, trying to meet or exceed 20.
Margin of success matters; it determines how well a character succeeds, affecting damage in combat, the amount of information gained in research, or persuasiveness in social rolls. Star Crusade measures margin of success in Victory Points: for every two full points a character succeeds by, they score one Victory Point according to the chart to the left.
A margin of success of 20 or above continues to accrue Victory Points: at 20 successes, a character scores 10 Victory Points, while at 22 he or she scores 11 VPs, and so on.
In contested rolls, Victory Points are often compared to each other, with the difference between the two character's Victory Points being net VPs for the winner of a contest. Depending on the situation, a net 0 VPs may result in success for the active party, the defending party, both parties or neither party.
Critical Successes and Mishaps
A roll of a natural 20 is a Critical Success: on such a success, characters receive an extra bonus of their choice: either a +4 to their next roll, 2 extra VPs on the critical success, or a free action. Players can propose alternate critical success bonuses of a similar "value."
Similarly, a natural roll of 1 is a Mishap. Mishaps often result in technological breakdown (like a gun jamming) or particularly good luck for an opponent. As a rule of thumb, a Mishap will often require a character to spend an action (and possibly a skill roll) resolving the Mishap or may give an opponent a bonus to their next roll, usually in the range of either a +4 to their goal or two extra VPs.
Many rolls are benefitted or hindered by synergy: life experiences, special skills, or innate attributes that help or hinder a character in accomplishing a task. Synergy modifiers are applied at the discretion of the GM, but come primarily from two sources, skills and blessings/curses.
Skills almost always provide positive synergy, where a character with a related skill gains a bonus to another roll. A character with a high Physick skill, for instance, may have a positive synergy when using Beastcraft to treat an injured animal. The required skill level to gain synergy is up to the GM, but as a general rule a skill of 5-6 will provide synergy on clearly applicable tasks (Physick to Beastcraft in the above example) and a skill of 7-8 will provide synergy on more attenuated applications (using Cultures to provide a bonus to Command when facing an enemy of the appropriate culture, for instance.) The skill level required to gain a synergy bonus is generally a point or two lower when the primary skill is very low (often 3 or less, as even basic knowledge of a related discipline can help a novice) or when the skill being used to gain a synergy bonus is very specific (one might only need 3 points in Lore: Oro'ym to gain a bonus to Physick when treating an Oroy'm).
Blessings and Curses also provide synergy for related rolls. Blessings usually provide positive synergy, while Curses usually provide negative synergy, though this can vary. The Short curse, for instance, usually provides negative synergy to athletic feats like jumping across chasms or trying to spot someone in a crowd; it might provide positive synergy, however, to a character trying to fit inside a small hole. Similarly, the Beautiful blessing might provide positive synergy for an attempt to seduce, flatter, or persuade someone, but it may provide negative synergy to a roll to remain unnoticed as the character's good looks draw attention.
While skills and blessings/curses are the most common sources for synergy, sometimes other factors can come into play. Being a psychic or theurge might provide positive or negative synergy in some situations, as might be being an alien, a foreigner, a priest or even a guilder. Synergy sources - like all bonuses and penalties - are ultimately up to the GM.
The calculate the synergy bonus or penalty a character receives, add up all their sources of positive synergy for a roll and subtract all their sources of negative synergy. If the result is positive, they receive positive synergy; if it is negative, they receive negative synergy. A character can only receive positive synergy or negative synergy for a given roll.
In contested rolls, only one side receives synergy. After calculating your synergy total, compare it to your opponent's total. Whoever has more positive synergy receives the bonus.
If your net synergy is positive - or you have the higher synergy bonus in a contested roll - you have positive synergy. For every source of positive synergy you have, you receive a +2 bonus to your roll, up to a maximum of +4.
For example, if Lady Sofia Decados is using the Charm skill to flatter the steward of her Hawkwood rival, and she has the Cultures (Hawkwood) skill at 5, she receives a +2 to her Charm roll. If she had Cultures (Hawkwood) at 5 and the Seductive blessing, she would receive a +4. If she had Cultures (Hawkwood), the Seductive blessing, and the Beautiful blessing, she would still only receive a +4 - only two sources of positive synergy can apply to a single roll.
If a character's net synergy is negative, they instead reduce their net VPs by the number of negative synergies they have. This cannot reduce their VPs below 0, and it does not reduce their chance of success.
For example, Lady Sofia Decados is being pursued by a trio of Scraver kidnappers, and she must leap between two buildings with a Strength + Athletics check. She rolls 2 VPs; however, she is Short, and so she reduces that to 1 VP. If she also the Asthmatic curse, her 2 VPs would be reduced to 0 VPs - still a success, but perhaps one that leaves her only barely hanging on to the far side.
Types of Checks
Characters make checks for a variety of reasons, including simple checks, contested checks, or extended checks.
Simple rolls are just that - a character makes a check with the appropriate modifiers and receives a number of VPs at the end of it. Simple rolls are often used in "character vs. environment" situations such as finding shelter in the woods, deciphering an ancient text, or unclogging a jammed slug gun.
Contested rolls are the heart of conflict, when two characters are competing to achieve the same goal. The classic contested rolls are in combat, but characters might also make contested rolls during a chase or footrace, while politically maneuvering at court, or while trying to resist psychic domination.
In a contested roll, characters compare VPs, and the person with the higher VPs wins and applies only the net VPs to their roll. Note that Synergy also works differently with contested rolls, as described above.
Some tasks take an extended amount of time, liking building a flitter from scratch or creating a network of revolutionaries inside a city. In such situations, staff sets a Success Target of VPs the character must achieve and a Work Period between checks. Every time the Work Period elapses, the character makes a roll and adds the VPs to a running total; they succeed when they reach the VP Target of their task.
Extended checks can have more or less risk. In some cases - like building a flitter - failures have no impact other than to accrue no VPs, though Mishaps might set the project back or even cause it to be abandoned. In other cases, extended checks are a race against time, with a character needing to reach their Target before some time period elapses.
Particularly risky extended checks may have a Failure Target, a number of failures that causes the project to fail or some other deleterious consequence. If the character accrues a number of failures equal to the Failure Target before they reach the Success Target, the task fails. For example, Lady Sofia might be trying to incite a rebellion amongst the vassals of Lord John Hawkwood; she can roll once per month, and needs to achieve 15 VPs before three failures or else Lord John will discover the plot and execute or imprison the conspirators she has been cultivating.
Checks can have intermediate Success or Failure Targets as well. For example, Jonas the Scraver's scrounger has broken down in the midst of the desert, and he has three days before he and his men die of thirst in the hot sun. He can make a Tech Redemption check every four hours and needs 20 VPs by the end of the second day or else he won't be able to make it back to the nearest friendly outpost. If he can make 10 VPs, however, he can get the scrounger running just enough to limp to a much closer Kurgan citadel - but what the Kurgans will do is a whole new challenge.
Similarly, Lady Sofia might have intermediate Failure Targets in the rebellion example above. On her first failure, Lord John may hear rumors of discontent among his lords, and on her second he may learn that there is a conspiracy against him, possibly triggering his own efforts to discover Lady Sofia before she succeeds or fails.
In special occasions, there may be checks that are hybrids of three main models. A noblewoman fleeing kidnappers in a darkened alley, for instance, may be running an Extended Check to get to 10 VPs - the amount needed to get out of the alley and into a crowded street - while the kidnappers are trying to catch up with her in a sort of contested roll before she does so. In a spy-vs-spy scenario, there might be two sets of Extended Checks with different skills and failure conditions, one from an intruder trying to steal valuable data and another from the security officer trying to stop him. All of these situations can be adjudicated with a set of appropriate conditions; as always, the system is designed to enable interesting action, not prevent it.