The game features the main character, who is referred to as the Trailblazer, traveling across planets through the Astral Express to help and connect the worlds while resolving disasters caused by "Stellarons" and other third parties.

Honkai: Star Rail follows the gameplay style of classic Japanese role-playing games where players build up a lineup of characters and control a team of up to four in turn-based combat.

Elements of open-world and dungeon exploration are present, with multiple mechanics including the gacha system, carried over (with slight differences) from Genshin Impact.

Each Path espouses an ideal: for example, the Abundance is based on the view that immortality is a blessing and that healing and altruism should be valued as a top priority.

Kafka takes hold of the Stellaron and inserts it into the body of an empty vessel generated by Silver Wolf (whose gender and name are chosen by the player).

The vessel (known as the Trailblazer in English and various other names in other translations of the game) awakens, after which Kafka erases their memory, informs them of the future that lies ahead and leaves.

The Astral Express crew receives a signal from Kafka, who wants the Nameless to settle a Stellaron incident on the Xianzhou Luofu, a massive planet-sized starship following the Path of the Hunt.

The crew finds and defeats Kafka in battle, after which she reveals she was sent to lure the Nameless to the Luofu to fulfill the prophecy laid out by the Stellaron Hunters' leader, Elio.

During this conflict, Dan Heng reveals that he is the reincarnation of a powerful exiled Vidyadhara criminal named Dan Feng during a battle with Blade, and assists the rest of the Astral Express and the Xianzhou Luofu army in fighting the Disciples of Sanctus Medicus and defeat Phantylia, forcing the Disciples of Sanctus Medicus and Antimatter Legion to retreat from the Luofu.

In the lead-up to the festival, the Trailblazer and Firefly encounter Sparkle, a member of a group of fanatic followers of the Elation known as the "Masked Fools", who knocks the two unconscious.

When they awaken, they find themselves in the dark reality of the Dreamscape, which is hidden from the public and are attacked by a monster called "Death," only to be rescued by the Memokeeper Black Swan.

Aventurine tells the Trailblazer that there are darker conspiracies involving the Stellaron and the Family's control over the Dreamscape and that Acheron is not what she seems before he reveals that Robin was also apparently murdered by "Death."

During the battle against the Trailblazer at the Clock Studios Theme Park, Aventurine threatens to detonate the Stellaron within them, forcing Acheron to "kill" him, revealing her true identity as an Emanator of Nihility.

After rescuing them from the confrontation between Acheron and Aventurine, SAM, revealed to be a surviving Firefly, explains to the Trailblazer and the Astral Express crew that "death" in the Dreamscape leads to Dreamflux Reef in the Land of the Exiles, a memory zone outside of the Family's jurisdiction and guarded by Penacony's Head of Security, Gallagher.

The Nameless confront Sunday at the Grand Theater, seemingly defeating him with Dan Heng's aid, but Black Swan reveals it was an illusion.

With help from Acheron, Black Swan, Robin, and Galaxy Ranger Boothill, the Astral Express crew escapes the illusion and truly defeats Sunday, restoring the Dreamscape and reality.

The city's leader Aglaea reveals that Amphoreus is on the brink of extinction and that the only way to reverse the planet's fortunes is to fulfill a prophecy of having a set of heroes - known as Chrysos Heirs - slay the world's twelve Titans and offer up their Coreflames to the Vortex of Genesis, with only six having been defeated so far.

Oronyx initially vehemently refuses until they recognize the Trailblazer as having captured the gaze of Fuli, the Aeon of Remembrance, and agree to grant their aid.

With their help, the Trailblazer and Castorice return to the waning days of Mydei's homeland and restore Nikador to his initial form, enabling Phainon to kill him.

Producer David Jiang hopes that Honkai: Star Rail can achieve the immersive feeling of "as if you are in the world of the work", and create a "playable animated series".

[46] In order to enhance player immersion, the production team integrated artificial intelligence technology into the behavior patterns of non-player characters.

[60] From April 29 to May 13, miHoYo undertook train advertisements on Xiamen Rail Transit Line 1 and jointly issued NFTs to promote the game.

[61] On mid-May, HoYoverse began to put up ads for the game in Japan, which are prominently displayed in Akihabara in Tokyo, as well as collaborating with Chichibu Railway in Saitama Prefecture to launch a special steam train service, which ran for a month.

[64] Eurogamer recommended the game for its "delightfully goofy humour, charismatic voice cast, and truly magnificent combat", despite the writers' tendency to "give one sentence explanations for important details, yet spend eight paragraphs overexplaining the simplest plot twist".

[73] Rock Paper Shotgun called the game "still in its early stages but (...) incredibly good fun to play", comparing it to "Star Ocean, but if everyone was hotter and you could gamble".

[77] On April 23, 2023, the day of pre-download, the game topped the free charts on the App Store in over 113 countries and regions,[78] and ranked first overall in mainland China, the United States, Japan, and South Korea.

[81] According to data from Sensor Tower, within the first 10 days of launch, the mobile version of the game generated over $100 million globally, with 44% of the revenue coming from China, 22% from Japan, and 12% from the United States.