Honkai: Star Rail's Duomension City and Planarcadia content added 122 distinct achievements, and a large share of them stay hidden until you trigger the exact condition that unlocks them. They span the main story, exploration, mini-games, combat, and a set of branch choices where only one trophy in a group can be earned per playthrough. The trickiest ones sit under the Fathom the Unfathomable category, which leans heavily on the Interplanar Jump! mode and odd interactions scattered around the map.
Achievement categories in the Duomension City batch
The 122 trophies fall into a few clear groups. Story-linked ones unlock automatically as you clear chapters, while the rest reward exploration, mini-game mastery, and curiosity around decorative objects.
| Category | What unlocks it |
|---|---|
| Main story | Roughly 11 trophies that pop as you pass major plot checkpoints. No hunting required. |
| Exploration and discovery | About 53 trophies for chests, secret rooms, hidden props, and optional map challenges. |
| Mini-game and unique interactions | Interplanar Jump! and similar challenges with strict conditions like staying airborne or triggering tiles. |
| World events and hidden encounters | Off-map events from interacting with unusual objects, NPCs, or unmarked zones. |
| Branch choice (mutually exclusive) | Quest decisions where only one trophy in a set can be earned per run. |
| Combat | Trophies for using specific abilities or winning under set conditions against new enemies. |
Full hidden achievement list
Below is every hidden trophy in this batch, grouped by its in-game category. Use it to check off what you still need before leaving Duomension City and Planarcadia.
| Category | Achievement | Unlock condition |
|---|---|---|
| Eager for Battle | Straight Fire Unreal Banger | Use Sparxie to activate "Engagement Farming" and build 9 "Straight Fire" stacks in one battle. |
| Eager for Battle | Trap Within a Trap | Use Sparxie to trigger "Engagement Farming" 10 times in a single action. |
| Eager for Battle | Lucky Charm | Use Yao Guang to trigger "Great Boon" 18 times in one battle. |
| Eager for Battle | May the Fortune Be With You | Collect 8 "Fortune Pouches" through Yao Guang's Technique "Untethered Glimmer Sails Far". |
| Eager for Battle | All for the Show | Have Aha use "Aha Instant" while dealing only 0 DMG. |
| Eager for Battle | Who's Laughing Now? | Defeat 1 enemy with Aha's "Let There Be Laughter". |
| Moment of Joy | Safety Comes First on Every Road | Get up close to a car in the middle of Duomension City's streets. |
| Moment of Joy | Go to A New World | Get hit by a hydro-car during an Interplanar Jump! sequence. |
| The Memories We Share | Time For Whispers | Infiltrate the CEO's conference room. |
| The Memories We Share | Aeonic Silence | Look at the portraits of the Aeons in the tavern. |
| The Memories We Share | The Fool and the Alchemist's Gate | Build your own elemental toilet. |
| The Memories We Share | Block Subspace | Uncover the secrets of the golden throne. |
| The Memories We Share | Reunion is Prologue | Witness Bequea's final journey back into the television. |
| The Memories We Share | If I Can Bring You Happiness | Witness Bequea and Rocket keep their promise to become family. |
| The Memories We Share | Hardboiled Detective | Stop the "Millennium Killer" with Ashveil using traditional methods. |
| The Memories We Share | Armchair Detective | Use Sparxie's modern methods to turn the "Millennium Killer's" tactics back on them. |
| The Memories We Share | Dandelion's Judgment | Let Sapone fulfill their wish. |
| The Memories We Share | The Crime is "Love" | Have Sorren accept lawful punishment. |
| The Memories We Share | Make Dough with Dignity | Choose to sell the pixel plane game to the IPC. |
| The Memories We Share | Walk with the Divine Sage | Reject the IPC's attempt to buy the pixel plane game. |
| The Memories We Share | Sunset VI | Fulfill Kraken's wish to roam beyond the sky. |
| The Memories We Share | Encyclopedia of Scams | Firmly reject Master Moon. |
| The Memories We Share | A Bet to End All Bets | Spend a fortune to become the only one of Master Moon's "disciples" to be fooled. |
| The Memories We Share | Homo Economicus | Escape when faced with Master Moon's eloquence. |
| Fathom the Unfathomable | When The Phantasmoon First Shone Upon Mortals | Go to the @Gate of Duomension City and gaze at the Phantasmoon. |
| Fathom the Unfathomable | Ascend to the Peak of Trailblaze | Reach the top of the Trailblazer's poster in Duomension City. |
| Fathom the Unfathomable | Catherine | After Sparxie pulls you into the 2D world, gain a new form and escape. |
| Fathom the Unfathomable | Hold On Tight and Put Phones Away | Ride an escalator once in Planarcadia. |
| Fathom the Unfathomable | Don't Try This At Home | Move against the escalator for 10 seconds or more. |
| Fathom the Unfathomable | Ping Pong | During "Jump Time" in Interplanar Jump! at Perdido Station, flip gravity to bounce the wispae back and forth. |
| Fathom the Unfathomable | Secret Storage Room | Enter the secret room in Graphia Academy's indoor gymnasium. |
| Fathom the Unfathomable | Lonely Are All Bridges | Reach the hidden plane during an Interplanar Jump! on Dovebrook Bridge. |
| Fathom the Unfathomable | Thorny Mask | Survive after taunting the Fool's Mask at the tavern. |
| Fathom the Unfathomable | Super Third Wheel | Witness the love of the paper crane. |
| Fathom the Unfathomable | Why'd You Do That? | Knock down the Billboard running in the tavern. |
| Fathom the Unfathomable | Here Used to Be Dragons | Find the treasure at the end of the Grand Treasury. |
| Fathom the Unfathomable | Let's Not Trailblaze Here | Open the secret room of the Golden Confessional. |
| Fathom the Unfathomable | Let Out a Wistful Tweet | Find a familiar feather in the tavern. |
| Fathom the Unfathomable | 2D Aficionado | Complete the Ultimate 2D Challenge on Blisstar. |
| Fathom the Unfathomable | Curving Arrow | In Interplanar Jump!, shoot an arrow that curves in flight. |
| Fathom the Unfathomable | Springleg Jack | Bounce 10 times in Trampoline: Introductory Training. |
| Fathom the Unfathomable | Let's Go Karaoke! | Eavesdrop on the melody from the karaoke bar in Duomension City or Dovebrook District. |
Branch choice trophies you can only get once per run
Several decisions lock you out of the opposite trophy in the same playthrough. Plan these before you confirm a choice, or expect to clear the content again to pick up the alternative.
- Hardboiled Detective or Armchair Detective — the method you pick to stop the "Millennium Killer".
- Make Dough with Dignity or Walk with the Divine Sage — selling the pixel plane game to the IPC versus rejecting them.
- Encyclopedia of Scams, A Bet to End All Bets, or Homo Economicus — how you respond to Master Moon.
How to unlock the trickier hidden achievements
When The Phantasmoon First Shone Upon Mortals
Step 1: Teleport to the @Gate area of Duomension City and head straight ahead along the path.
Step 2: Turn at the corner and interact with the marked point.
Step 3: Follow the route to the next waypoint and gaze at the Phantasmoon to finish the trophy.
Ping Pong
Step 1: Travel to Perdido Station and interact with the button to enter Interplanar Jump! Difficulty I.
Step 2: During Jump Time, flip gravity repeatedly so the wispae bounces from one end of the arc to the other several times. The trophy unlocks once you keep it ricocheting.
Springleg Jack
Step 1: Talk to Xiao Gao to start the Trampoline: Introductory Training interaction.
Step 2: Pull the lever above, then bounce back and forth at the marked spot until you hit 10 bounces.
Let's Go Karaoke!
Step 1: Teleport near the karaoke bar in Duomension City or the Dovebrook District and walk up to its doorway.
Step 2: Stand in front of the door and wait. The melody plays for about 5 to 6 minutes before the trophy registers, so stay put.
How to confirm a trophy unlocked
When the condition is met, an achievement banner appears at the top of the screen, and the trophy moves into your completed Achievement list with its Stellar Jade reward attached. If a hidden one does not pop, the usual cause is a condition you did not fully satisfy. For example, falling short of the required stack count, choosing the opposite branch in a mutually exclusive set, or leaving an Interplanar Jump! stage before reaching the hidden plane.
Clearing the whole set is one of the steadier ways to bank Stellar Jade, since each trophy pays out on unlock alongside the larger completion rewards. Work through the branch choices first, then sweep the Interplanar Jump! and tavern interactions, and the rest of the count falls into place as you explore Duomension City and Planarcadia.