SOMA is a linear story horror game, but it is easy to lose time in PATHOS-II because the stations look similar, the enemies all follow different rules, and the achievement list hides one important missable near the end. This guide is written as a practical story walkthrough with puzzle reminders, monster handling, and a 100 percent cleanup plan.
Spoiler warning: this walkthrough names locations, late-game objectives, enemy behavior, the ARK simulation solution, and achievement triggers. If you want the full first-play impact, use only the first two sections, then come back when you are stuck or ready to clean up.
Best Completion Plan
- For a first playthrough, play on the mode that matches your tolerance for horror. Safe Mode is a good choice if chase pressure would stop you from enjoying the story; this walkthrough still explains monster behavior for normal play.
- Do not restart for achievements during the early and middle game. Most achievements are story-triggered and unlock naturally as you move through the main route.
- The one achievement to actively protect is Endangered Species. Near the end at Tau, speak with Sarah Lindwall before you disconnect her life support or take the ARK onward.
- Keep manual saves or cloud backups only if you like extra insurance. SOMA uses autosaves, and the route is linear enough that a careful single run can clear everything.
- When a monster appears, learn the rule for that monster instead of using the same tactic every time. Some react to sound, some to eye contact, some to movement, and some are best handled by simply leaving.
- Stay after the credits. The final achievement is tied to the post-credits sequence, not the moment the launch sequence begins.
Quick Route Overview
| Area | Main Goal | Watch For |
|---|---|---|
| Toronto prologue | Drink tracer fluid, visit Munshi’s lab, complete the scan. | Read the office code from the desk instead of brute forcing it. |
| Upsilon | Repair the Omnitool, restore comms, and leave for Lambda. | Construct encounters and the choice of which power source to shut down. |
| Seafloor to Lambda | Reach Catherine and move her into the Omnitool. | Slow scavengers outside and the Flesher inside Lambda. |
| Curie and Delta | Escape the ship, reach Delta, call the Zeppelin, and travel to Theta. | Flesher maze, reactor escape, and the Zeppelin code sequence. |
| Theta | Prepare the ARK scan, solve the simulation, and attempt the DUNBAT plan. | Proxy sound rules, Akers, Brandon Wan simulation, and elevator repair. |
| Omicron | Lift quarantine, build the power suit, and transfer into the new body. | Quarantine code 5422, suit sync 157, and Robot Head movement rules. |
| Abyss and Tau | Reach Tau, collect the ARK, and make the final trip toward Phi. | Leviathan lights, Jin Yoshida, and the missable Sarah conversation. |
| Alpha, Phi, Omega | Resolve the WAU choice, load the ARK, and launch the satellite. | Leviathan cover, power-pack routing, and the post-credits scene. |
Walkthrough
Toronto Prologue
Start in Simon’s apartment. Explore if you want background flavor, then find the tracer fluid in the desk drawer and drink it. Take the subway to Munshi’s lab. In the office, check the desk for the code and use the computer if you want extra setup before the scan. Once you sit in the chair, the game moves you into PATHOS-II.
There is no achievement pressure here. The prologue exists to set tone and make the later station documents more meaningful, so do not rush past every email on a first run.
Upsilon: Omnitool And First Power Route
After waking up, follow the facility route until you reach the broken window and Omnitool work area. Use a loose object such as the fire extinguisher to break glass when required. Insert the Omnitool at the terminal, unlock the tool box, take the chip, install it, then update or manage the chip from the same workstation. Remove the Omnitool when the update finishes.
After meeting Catherine by radio, restore power and move toward the communications center. The first Construct encounter is a lesson in not panicking: crouch, keep distance, and go for the valve, ladders, and doors rather than hiding forever. Later, when choosing how to open the route forward, shutting down Flow Control creates a Construct patrol, while using the power next to Carl avoids that patrol but leaves him suffering. The story consequence is moral rather than achievement-based.
At the station control console, use Carl Semken’s ID tag for login context, enable the needed systems, and solve the Lambda communication puzzle. When the exit opens, leave Upsilon and follow the seafloor lights toward the shuttle station.
To Lambda
On the seafloor, stay close to lit paths and follow the helper bot when it cuts open the shuttle station. The scavenger-style enemies outside are slow; do not stare at them for drama, but you can usually walk or run past if you keep to the route.
Inside the shuttle station, collect the flashlight and restore enough power to use the tram. Disconnect the WAU growth from the power source, return to the shuttle, insert the Omnitool, pull the switches, and choose Lambda. After the crash, do one important thing before leaving: take the Omnitool back. If you forget it, you will simply have to walk back.
At Lambda, answer Catherine’s call, enter the station, and find her in the monitor room. Move Catherine into the Omnitool. The Flesher in this area is more about proximity and eye contact than normal stealth. Avoid staring, keep moving when the path is clear, and do not trap yourself in a dead end.
Curie And Delta
The Curie section sends you through a wrecked, vertical ship and a Flesher patrol. The useful rule is simple: do not treat every side room as mandatory. Move along the corridors, use dead ends only as short hiding places, and avoid prolonged eye contact. When you reach the reactor sequence, remember the route back to the escape vessel before you pull the final power sources; the return is a chase, not a search section.
At Delta, use the communication equipment to call a Zeppelin. The signal puzzle asks you to line up the antenna and signal equipment until the system gives the Zeppelin number. The achievement references confirm code 049 for the Zeppelin request. After it arrives, take the stun gun from the opened toolbox area, disable the correct robot for a chip, install that chip in the Zeppelin, and travel to Theta.
Theta: Power, Brandon Wan, And The ARK Room
Theta is the longest station and the easiest place to feel lost. Start by entering the hangar, breaking the window into Catherine’s room, and letting her unlock the route. You need a cartridge, power, a successful Brandon Wan simulation, the ARK simulation setup, and finally an elevator repair.
When you go down to restore power, you meet the Proxy rule set. Proxies are blind, but their hearing is severe. Crouch, avoid running, avoid kicking loose objects, and do not toggle the flashlight near them. If the Proxy hears the router or power switch, hide behind solid cover and move only after it settles.
For Brandon Wan, gather his context from his room and records, then use the scan-room setup to make the simulation believable enough to obtain the needed information. Community route notes disagree on small optional setup details, so the safe rule is: if the run fails, add the missing Brandon/Alice context the station points you toward, then run it again before returning to Catherine.
In the ARK room, the resource allocation puzzle can be solved by activating the modules the right side marks as required. If you want a direct checklist, use this set:
| ARK Simulation Modules |
|---|
| sys_physics_rigid |
| sys_physics_fluid |
| sys_phys_buoy |
| sys_wmod_atmo |
| sys_interface_scan |
| sys_wmod_dynlight |
| sys_gen_veg_adv |
| scn_forest |
| pkg_soma_hum |
| env_mod_river |
| ext_moon_full |
After the simulation runs, lower the resource allocation when prompted, pause at the dummy stage, run the diagnostic, and continue. The DUNBAT attempt fails as part of the story and unlocks Plan B. It is not a bad ending or a failed puzzle.
Escaping Theta
After the DUNBAT failure, use the prepared ladder/duct path and move into the elevator repair route. If you want to reduce Akers pressure, use the security room and door controls to reach Brandon’s body without smashing every shortcut window. Retrieve the chip, format or update it at the security terminal, return to the elevator, install it, and start the elevator.
The fall and mind-coral sequence are scripted. After you break free, work through the maintenance path using vents whenever they are available. In the Proxy gauntlet, slow movement is more valuable than bravery. Throwing an object can pull a Proxy away from a door, but do it deliberately and then leave; do not keep experimenting after the path opens.
Pre-Omicron And Quarantine
Once you are back outside, follow the industrial path toward Omicron. The exterior route asks you to use ladders, catwalks, water controls, and a tunnel to reach the quarantine control building. Restore the power by using the manual override levers and wheels, then use the Omnitool at the terminal.
The quarantine code is 5422. The nearby malfunctioning terminal provides the clue, so if you prefer in-world solving, interact with it before entering the code. Once quarantine is lifted, flood the chamber again, exit, and enter Omicron.
Omicron: Building The Power Suit
Inside Omicron, follow signs to the Dive Room and let Catherine explain the suit plan. You need three parts: a chip, structure gel, and a power pack. The station is layered, so clear them in a simple order:
- Go to the robot repair area and complete the terminal puzzle to get the chip.
- Use the containment controls to access the gel lab, move the chip through the gel procedure, and take the structure gel.
- Go to the upper-floor power room and remove the power pack from the rear panel.
- Return to the Dive Room, install everything in the suit, and start the transfer sequence.
The Robot Head enemy in Omicron reacts to movement more than sight or sound. When it flares up, stop moving for a few seconds. Crouch and take small movements when it calms down. After you have the needed suit parts, expect a chase toward Catherine rather than trying to sneak the entire return.
The suit sync hint is 157. After the body transfer, take Catherine, leave through the round door, and start the descent into the Abyss. If the elevator stalls, climb to the top side and fix the electrical box before sitting again.
Abyss To Tau
The Abyss path relies on lights and cables. Pull the first light switches, follow the blue and green lamps, and use the helper bot route until the path breaks. When the bright anglerfish-style lure appears, do not walk toward it. Follow the cable and the safer lights instead.
The Leviathan is mostly handled by movement and cover. Early on, stay near lights and keep going. Later, after Alpha, it becomes more aggressive, and the right answer is to hide behind cave walls, rocks, or scrap when the music and attack cues intensify.
Tau And The Missable Achievement
Tau is the only achievement danger point in the game. Move through the station, deal with Jin Yoshida, and reach the infirmary. Jin is fast and dangerous, but he can be slowed briefly by looking at him. Do not stare forever; use short eye contact to hold him while doors open, then move around tables, through rooms, and up ladders as soon as you have a route.
When you find Sarah Lindwall, talk to her before disconnecting her life support. This is the trigger window for Endangered Species. Community achievement guides agree that this is the one achievement many players miss because the story pressure makes it tempting to take the ARK and leave immediately.
After Sarah gives you access to the ARK, carry it back through the route. When water fills the area and the ARK jams, release the three pillars/blocks that stop the water flow, follow the ARK, and continue toward Alpha.
Alpha, Phi, And The Omega Space Gun
At Alpha, the WAU choice is a story decision, not an achievement split. Make the choice you want, then escape. The Leviathan chase afterward is more demanding than the earlier light-following sequence. Keep running when the route is open, and take cover when the attack cue rises.
At Phi, go to the back room and plug in Catherine. Take the ladder down, grab the power pack from the electrical room, use it to open the ARK room, and bring the ARK to the loading platform. You then need that same power pack again to power the launch room, so do not lose track of it.
Load the ARK into the launcher, start the launch preparation, take Catherine/Omnitool, enter the launch dome, and follow the final catwalk to the control point. Stay through the credits for the post-credits sequence and The End.
Monster Survival Rules
| Enemy | Where It Matters | Best Response |
|---|---|---|
| Construct | Upsilon | Crouch, keep moving, use boxes and corners briefly, and leave once the route opens. Doors are not perfect safety. |
| Scavenger / crawler robots | Early seafloor routes | Stay out of the direct path and keep moving. They are slow enough that panic is more dangerous than the enemy. |
| Flesher | Lambda and Curie | Avoid prolonged eye contact, keep distance, and move through corridors instead of hiding in one corner forever. |
| Proxy / Terry Akers | Theta | Crouch, reduce sound, avoid flashlight toggles near the enemy, and use thrown objects only when you already know where you are going. |
| Robot Head | Omicron | Move slowly, stop when it lights up or reacts, and wait for it to calm down before crawling onward. |
| Leviathan | Abyss and after Alpha | Follow lights early; later, run between cover and hide when the attack cue rises. |
| Jin Yoshida | Tau | Use brief eye contact to slow him, keep doors and furniture between you, and leave as soon as a big door or ladder route opens. |
| Johan Ross | Omicron, Tau, Alpha | Do not treat every appearance as a combat encounter. Most appearances are story pressure rather than a normal monster hunt. |
Achievements
SOMA has 10 Steam achievements. The Steam public achievement page confirms the names and global percentages, while readable community achievement references help place the exact story triggers. Only Endangered Species needs special attention.
| Achievement | Trigger | Missable? |
|---|---|---|
| Answering the Call | Talk to Catherine at the early phone station. | No |
| Chasing Catherine | Reach Lambda after the shuttle crash and continue Catherine’s route. | No |
| Stranded | Crash-land at Delta. | No |
| The DUNBAT | Reach Theta after arranging the Zeppelin route from Delta. | No |
| Plan B | Complete the Theta preparation and watch the DUNBAT plan fail. | No |
| Killed the Dream I Dreamed | Escape Theta through the maintenance route. | No |
| A New You | Complete the Omicron body transfer and leave in the power suit. | No |
| Endangered Species | Meet and speak with Sarah Lindwall at Tau before disconnecting her. | Yes |
| Your Expressway to the Stars | Reach the Omega Space Gun / final launch route with the ARK. | No |
| The End | Finish the post-credits sequence. | No |
Common Mistakes
- Trying to fight monsters: SOMA is not a combat game. Objects can occasionally distract, but throwing things at enemies or testing hitboxes usually makes the situation worse.
- Using one stealth rule for every enemy: Proxy sound rules do not solve the Flesher, and Flesher eye-contact rules do not solve Robot Head. Learn the local rule.
- Skipping Sarah too fast: Speak to Sarah before disconnecting her. If you skip that conversation, you can miss Endangered Species.
- Copying a final ID from a guide: The late-game ID is player-specific. Read the monitor that displays your name.
- Over-searching during chases: Many chase sections are meant to be escaped, then explored only if the game gives you quiet control again.
- Walking toward pretty lights in the Abyss: Some lights mark the route; one is a lure. Follow cables, signs, and repeated path lights, not every bright object.
Sources And Credits
This guide was checked against the official SOMA Steam page, Steam app metadata and achievement data, the official site listed by Steam at somagame.com, and readable Steam Community walkthrough, achievement, ARK puzzle, and enemy-behavior references. Public images are official Steam screenshots. No community-guide screenshots are used.