To progress through Mouthwashing, follow the current objective and date card: open Cargo with 4517, free Daisuke using the axe, prepare Curly's birthday cake, and return to the medical room when directed. This walkthrough follows the game's nonlinear presentation rather than rearranging events into a chronological story.

Full spoilers begin below, including deaths, the crash revelation, body horror and the final scene. For spoiler-light help, use only the section matching your current location. Specific solutions are in the cake puzzle guide and gun-case code guide.

Progression is paraphrased from 伏双双's player-authored walkthrough, with achievement details checked against Steam's official schema. The community guide is not an official developer walkthrough, and this article does not claim a firsthand completion test.

01

Begin in the cockpit, then open Cargo

In the opening crash-day scene, inspect the control lever, take the Emergency Key from the cockpit locker, sit at the controls and use the key to disable autopilot. Leave the cockpit. When doors and the toy horse obstruct your progress, follow the changing corridor route, retracing your path when a door refuses to open.

After the transition to two months after the crash, finish the conversation and go downstairs. Enter the cockpit through the automatic door at the corridor's end and collect the Code Scanner from the floor. Scan Cargo's barcode and enter 4517.

For the optional Cheater achievement, the official condition requires opening Cargo before acquiring the scanner. That differs from the ordinary discovery route above.

02

Rescue Daisuke and read the company news

Seven days before the crash, finish speaking with Anya, then find Jimmy and Swansea downstairs near the utility room. Daisuke is trapped in emergency foam. Scan the covered code for the axe case, enter 2609, retrieve the axe and use it on the foam.

Speak with Jimmy outside, then head toward the cockpit. Continue through the distorted space until you reach it again. After the interrupted conversation, collect the company news from the printer. In the following television sequence, approach the screen and change channels using its upper-right control. Continue into the post-crash Cargo revelation.

03

Make the birthday cake

Six days before the crash, go to the lounge counter and inspect the recipe booklet. Take the water pouch and obtain Gelatin with 4213 and Sweetener with 2341 from the dispenser. Combine Water + Gelatin to make Cake Base, then combine Cake Base + Sweetener.

Place the finished cake on the dining table and interact with the knife. Before serving it, achievement hunters can make the birthday mocktail: Water + Tonic, then add Sweetener. Tonic's dispenser code is 1324. Steam's Wasteful achievement specifically concerns the specialty mocktail at Curly's birthday. The cake guide separates the two preparations.

04

Return to Curly and check the crew

In the next medical-room visit, inspect Curly, find Anya in the cockpit and return to administer his painkillers. Open Curly's mouth before using the medicine.

The story then interrupts ordinary ship exploration with a disturbing dining scene. Sit at the cake and speak with Curly. When prompted to find a knife, follow the available route toward the cockpit, retrieve the axe and return to the table to use it on Curly.

When the post-crash crew check resumes, leave Cargo and speak with Daisuke on the floor; collect the mouthwash. Upstairs, speak with Anya at the table and Swansea near the large screen. Take the axe, clear the foam outside medical and collect the painkillers and isopropyl. Speak with Anya and treat Curly again.

05

Barricade the door and investigate medical

During the scene marked six hours before judgment, hold the door, collect the metal pipe from the wall and take nylon rope from the cabinet. Use both items on the door to secure it.

The next pre-crash conversation with Anya supplies story context. Later, four months after the crash, Daisuke alerts you to the medical-room situation. Inspect its entrance, then go downstairs and speak with Swansea outside the utility room. Match these scene cues to your current objective: the changing dates are deliberate.

06

Recover mouthwash past the blind creature

At eight hours before judgment, take the stairs near medical toward Cargo. Bring up the scanner and continue down the descending route until the scene transfers you to a platform. Your objective is the mouthwash bottle.

The community walkthrough describes the creature here as reacting to sound. Its arrival is preceded by a sharp noise: stop moving while it is present, then resume when it disappears. Retrieve the bottle and use it on Daisuke when the scene returns. This section is a progression route; the separate Any% Glitched achievement has an official 35-second condition and should not be confused with an ordinary completion requirement.

07

Obtain the utility-room key and the gun

In the three-month post-crash scene, inspect the lounge recipe instructions. Combine the inventory mouthwash with isopropyl, then combine that base with Sweetener to create the spiked drink. These are fictional game actions involving toxic substances. Sweetener is beneath the lounge bedding; isopropyl is in the cabinet outside medical unless already collected.

Give the drink to Swansea, collect the dropped utility-room key and unlock the room. Continue through the damaged-vent and medical-room events involving Daisuke and Anya.

After the one-day-before-crash conversation with Anya in the cockpit, the story returns to six hours before judgment. The medical Protection Kit opens with 739. Its clue can be scanned inside the cockpit locker. For Taking Notes, enter the remembered code without returning to the cockpit during this objective. Take the gun and leave medical.

In the following crash-day flashback, speak with Anya in medical, then Jimmy outside the cockpit, and enter it. When the story returns to the later dining scene, place Curly on the table, pick up the knife and use it to continue.

08

In the first late surreal sequence, enter the vent. At the note warning against turning back, keep facing it and move backward. As new landmarks appear, face the left grille, then the right grille, then the red note on the left while continuing backward. Follow the route into the cabin and down through its floor hatch.

After leaving the next vent, pick up the gun near Swansea and use it. In the graveyard, approach the wooden gate. Listen for the bell and watch the screen-edge warning: the community guide describes Swansea attacking from behind. Turn toward him and shoot when he closes in; continue until the scene changes.

09

Finish the television and scanner sequences

Follow the route back to Curly. Inspect the television and take his leg from the cake imagery. Use the four red wheels on Curly to adjust the screen; the linked community walkthrough provides the visual arrangement. Open his mouth, use the leg and return to the television, controlling the Jimmy inside it toward Curly.

In the next sequence, collect the ultrasound scanner and examine the red tissue. Locate two parasites, one on each side, using the strengthening heartbeat as a proximity cue. Clear them, then continue into the crawling creature encounter. Avoid its path as it pauses before attacking; survive until the transition. Follow the stairs and speak with Polle.

At the final return to the ship, pick up Curly from the dining table and place him in the cryopod. Jimmy's suicide follows. Curly is alive when placed in cryostasis; a later rescue is not shown. For the distinction between these events and their interpretation, read ending explained.