Confirmed campaign premise
The campaign opens with Colonial Marines responding to a distress signal. Daybreak's official launch announcement says the operation brings them into conflict with Xenomorphs, Synthetics and rogue bioweapon threats.
That premise is the safe spoiler-light foundation. The supplied official material does not publish a complete mission-name list, objective order or encounter-by-encounter walkthrough, so this guide does not manufacture those missing details.
Reported mission count and length
GamesRadar reports that the campaign contains 15 missions and takes approximately eight to ten hours to complete. At the broadest documented level, the campaign is structured as 15 missions; the time estimate remains an attributed review finding rather than a guarantee for every player.
Difficulty, squad experience, retries and the pace used to inspect environments can move an individual playthrough outside that range. Use the estimate to understand campaign scale, not as a timer or proof of a fixed mission duration.
Solo and cooperative campaign structure
The game supports squads of up to four, and the Xbox Store lists both single-player and online co-op for two to four players. GamesRadar reports that AI synth companions fill empty squad slots when human teammates are absent.
Cross-platform co-op and cross-platform voice chat are confirmed by the official site. For a mixed-platform campaign, update every copy before starting; launch notes included fixes for cross-platform voice chat and several Xbox invite and network problems.
Do newcomers need the first game?
GamesRadar says playing the first Aliens: Fireteam Elite is not required to follow the sequel's story or mechanics. A newcomer can therefore begin with the distress-signal premise without treating the first campaign as mandatory homework.
No supplied source confirms character, progression or save-data carryover from the first game. Keep that separate from story accessibility: being able to understand the sequel does not prove that an old Marine or inventory transfers.
How to use this overview without spoilers
Plan for a 15-mission reported campaign, pick complementary class roles and decide whether absent squad slots will be handled by bots. Use the official premise to set expectations while avoiding uncited mission names or objectives passed around as fact.
For exact objectives, rewards and current mission behavior, rely on the live game and later official notes. The launch patch already changed a wide range of abilities, perks, weapons, audio and platform behavior, showing why a static launch walkthrough can age quickly.
