The core setting is the Next Generation era: specifically 2371, during early season 3 of Star Trek: Deep Space Nine and shortly before the premiere of Star Trek: Voyager. In the Alpha Quadrant, the United Federation of Planets, still scarred from the Cardassian border conflict and the Borg incursion at Wolf 359, has been rocked by the dual blows of the Maquis insurrection and the bloody first contact with the tyrannical Dominion. In the Beta Quadrant, the secretive Romulan Star Empire glares daggers at the Federation across The Neutral Zone, while the fractious, feudal Klingon Empire is allied to the Federation on paper but still a frenemy at best. The Gamma and Delta Quadrants remain virtually unexplored.
Into this calamitous time, your dashing, intrepid crew of Badass Bookworm Starfleet officers are thrown.
The game system encourages prospective Game Masters to approach play in a format much like a Star Trek TV episode, with official missions broken up into "scenes"; some points pools replenish at the start of a scene. Skill checks, called Tasks, rely on six Attributes and six Disciplines, which are added together at GM discretion to create a range that a player must roll inside on 2d20 a given number of times to succeed. Tasks can be modified based on a given character's Traits (primarily their species), Values (a set of abstract statements about things the character has experienced or believes), and Focuses (skill specializations).
Optional rules also allow for gameplay in the time periods of Star Trek: The Original Series or Star Trek: Enterprise; later supplements added support for the setting of Star Trek: Discovery's first two seasons. In 2020, Modiphius also released an alternate Klingon Core Rulebook to allow gameplay from the Klingon Empire's point of view.
This game includes examples of the following tropes:
- Alien Non-Interference Clause: The core rulebook has an extensive discussion of the origins and history of the Prime Directive and its various interpretations. It is also cited in nearly every official mission and campaign.
- Armor-Piercing Attack: Weapons with the "Piercing" quality ignore a certain number of points of Resistance for each Effect rolled.
- Fictional Document: Sidebars in the rulebooks include quotations from a wide range of authors regarding events in Star Trek, usually but not always related to the topics on the page.
- Gender Is No Object: Justified by the Federation's emphasis on egalitarianism: a sidebar in the core rulebook specifically states that "characters in Star Trek Adventures may be of any ethnicity, religion, sex, gender, sexuality, and so forth, without limit or restriction."
- Humans Are Average: Humans uniquely get to pick where to put their racial bonus Attribute points.
- Justified Tutorial: The Starter Set includes a three-mission campaign, A Star Beyond the Stars, that is organized as a walkthrough for the Game Master on how to use the game system.
- Massive Race Selection: The core rulebook alone has stats for eight player races and seven NPC races. Add the supplements and the total is seventy altogether.
- Minmaxer's Delight:
- The Quick to Action talent. During the first round of combat, the players can keep initiative for zero cost to their momentum. Since STA runs on a Players-Opponents-Players turn format this quickly results in the players essentially being able to do major damage to the opponent before they even get to start. A very common houserule amongst STA GMs is to limit it to one time.
- Anything with the Vicious Quality applies. For every effect rolled, the "effect" gained is an extra point of damage. On very high damage rolls sufficient effects can be One-Hit Kill.
- Phasers during space combat are significantly more powerful than Torpedoes due to the "Versatile" quality, which gains momentum per effect rolled. A very well rolled Phaser shot as a result can max out the momentum pool immediately and have overflow momentum that can used immediately for extra damage.
- Melee Combat on the ground is very powerful and frequently preferred by players over energy weapon combat. First, Melee Combat is Turn Agnostic as every melee check is an opposed task, and whomever wins the rolls is the attacker, meaning that players can frequently spend momentum for extra dice to overpower an enemy attacker and then defeat them.
- In addition, the Talent Mean Right Hook gives melee combat the aforementioned "Vicious" quality, making it much easier to knockout an enemy despite the general lower damage output of hand-to-hand combat.
- General Melee Weapons are also very powerful in their own right despite coming with a Threat cost, but also have Vicious 1 quality and have higher base damage than unarmed strikes, meaning that while they minimally increase the GM's potential to fight back, the players have a significantly higher chance of giving the enemies a bad day.
- Hand Phasers "Charge" quality is also very popular though in a more Boring, but Practical way. As a minor action, a player can use a Charge to activate a stun or wide beam effect. If the player is lucky and rolls an effect as well the player can easily trigger a Wide Angle Stun Area of Effect.
- In Non-Combat talents, the Advanced Sensors Talent for starships is almost universally taken because it reduces the difficulty of all scans done by the ship by one. This makes it unlikely the players will have Failed a Spot Check when using the ship's sensors very unlikely as when using the ship's sensors the players are rolling three dice and the odds of a what would be a Difficulty 5 or 4 task (which would be reduced to 4 or 3 with the talent) appearing are very slim for most GMs.
- Related to this - Science Officers also get a bonus free Obtain Information anytime they do a scan with the ship's sensors, meaning that Science heavy ships frequently can acquire the required information immediately.
- Mythology Gag: The first mission of A Star Beyond the Stars sends the PCs in search of the USS Alcubierre, which went missing while testing a new warp drive variant. Miguel Alcubierre is the theoretical physicist who formulated the theory behind the Alcubierre Drive, inspired by Star Trek's warp drive.
- P.O.V. Sequel: The Klingon Core Rulebook is a rewrite of the original core rulebook from the Klingon Empire's point of view instead of the Federation's.
- Pyrrhic Victory: Narendra III, according to Romulan Admiral Kylor Jerok in a sidebar. Yes, the Romulans won, but the destruction of the Klingon outpost and the Enterprise-C only reinforced the Federation-Klingon alliance, freezing the Romulans out of input into galactic events.
- Realpolitik: A Fictional Document from the Zakdorn Defense Institute (dating to circa 2360) recommends against Federation intervention in the Occupation of Bajor, arguing that ejecting the Cardassians from Bajor would require a proper war that the Federation can't afford, and that Gul Dukat's appointment as prefect is likely to stiffen the Bajoran Resistance and let them force the Cardassians out on their own.
- The Six Stats: Characters' and ships' stats are given in two groups of six. These are combined one each at GM discretion to create the target for a Task roll.
- Characters have the Attributes (ranges from about 6 to a cap of 12) of Control, Fitness, Presence, Daring, Insight, and Reason, and the Disciplines (ranges from 1 to 5) of Command, Security, Science, Conn, Engineering, and Medicine.
- Ships have the Systems of Comms, Engines, Structure, Computers, Sensors, and Weapons, and the Departments of Command, Security, Science, Conn, Engineering, and Medicine.
- Series Continuity Error: Page 42 of the core rulebook repeats the misconception that different ships had their own unit patches in Star Trek: The Original Series, originally caused by a costuming error in "The Omega Glory".
- Skill Scores and Perks: Disciplines are essentially skill scores, while Talents are like Perks, giving alternative gameplay options in specific circumstances. Traits, Values, and Focuses can also be used to modify Tasks: an unfamiliar species Trait might make treating an illness more difficult, a Value that is applicable to a given situation allows a PC to spend Determination to gain an advantage, and rolling for a Task if a character has an applicable Focus scores an extra success.