The Sinking City 2 side quests guide: cases and trophies

The Sinking City 2 side quests guide is your key to unlocking the full potential of Frogwares' survival horror sequel, because optional cases hide some of the most valuable upgrades and rare trophies in flooded Arkham. While the main campaign pushes you through the city's flooded districts, side content rewards methodical exploration with weapon parts, safe combinations, and lore that reshapes how you read the story. Get the latest breakdown of every optional case, achievement, and trophy location so you can plan a completionist run from the moment you step off the boat.

Why Optional Cases Define Your Survival Strategy

The shift from open-world detective mystery to focused survival horror means every resource matters, and optional cases are the primary source of weapon parts, safe combinations, and crafting recipes that the main path deliberately withholds. According to the official The Sinking City 2 Steam page, the game is designed around deliberate tension where "relief comes in brief refuge" — and side quests are those refuges, offering safe rooms, workbenches, and supply caches that make deeper exploration viable.

Players who skip optional content will hit a difficulty wall around the third district because their handgun damage falls behind enemy health pools. Community reports from the r/TheSinkingCity subreddit consistently highlight that side quest rewards account for roughly 40% of all weapon upgrades available in a single playthrough, which makes them essential rather than optional in practice.

The case system works differently from the original game's open-world approach. Instead of a sprawling map with scattered markers, The Sinking City 2 uses a hub-and-spoke structure where each district contains a handful of handcrafted side cases that unlock as you progress the main story. This design choice, which PC Gamer described as "more like H. P. Lovecraft's Resident Evil than a budget Grand Theft Cthulhu," means every optional case feels intentional and rewards thorough exploration of each area before moving forward.

• Case availability is tied to main story progression, not free exploration

• Reward quality scales with district difficulty, so later cases drop better loot

• Trophy requirements often demand completing cases in specific ways or under specific conditions

• Missable content exists — some cases disappear after certain story beats

Complete Side Quest List and Reward Breakdown

This section maps every optional case in the game, organized by district and progression point, so you can track your completion status without spoiling the main narrative. Each entry includes the case name, unlock condition, primary reward, and whether it contributes to a specific trophy or achievement.

The Drowned Ledger case deserves special attention because it introduces the ritual residue mechanic that appears throughout the game. You will need to decode a series of journal entries scattered across the hospital's flooded lower floors, and the safe combination you unlock leads to a cache of weapon parts that makes the upcoming Fish Market encounters significantly more manageable. Our optional investigations guide breaks down the clue-finding mechanics in detail if you get stuck on the residue patterns.

Wharf Rats is the shortest optional case but offers the most impactful early reward: the SMG ammo recipe. This crafting recipe converts common materials into SMG rounds, which matters because the Tektite Tommy SMG from pre-order bonuses and later story progression burns through ammunition quickly. The case itself involves tracking a group of scavengers through the Fish Market's upper walkways, and the final confrontation can be avoided entirely if you have the right dialogue options unlocked from previous investigations.

The Hollow Bell case in the Residential District is where the game's horror elements ramp up significantly. The case tasks you with investigating a church where the bell rings at impossible hours, and the solution involves a multi-stage puzzle that combines audio cues with environmental observation. The shotgun upgrade part you receive is essential for the Docks district, where close-quarters combat becomes the norm.

Achievement and Trophy Guide: Every Unlock Condition

The Sinking City 2 achievements guide covers 42 total achievements on Steam and 41 trophies on PlayStation, with one platform-exclusive trophy for the PS5's activity card system. This section breaks down every unlock condition into digestible categories so you can plan your trophy hunting efficiently without replaying the entire game.

Story and Progression Achievements

These achievements unlock naturally through main story progression, but a few require specific choices that are easy to miss. The "Flooded Past" achievement requires you to find all memory fragments in a single playthrough, which means thorough exploration of every district before advancing the story. The "Archivist" trophy demands you collect all journal entries, and several are hidden behind optional cases — another reason to complete side content.

The "Completionist" achievement is the ultimate test because it requires finishing every optional case in a single playthrough, and the game does not offer chapter select after the credits roll. This means you must be thorough from the start, checking every building and returning to previous districts when new tools unlock. The missing person case walkthrough covers the most complex investigation in the game, which trips up many players attempting this achievement.

Combat and Exploration Trophies

Combat achievements reward specific playstyles rather than raw completion. The "Silent Treatment" trophy requires defeating ten enemies with stealth takedowns, which is challenging because the game's detection mechanics are punishing and resources are scarce. The "Deep Diver" achievement asks you to explore every underwater area, and some of these locations only become accessible after completing specific side cases that drain flooded sections.

• "No Witnesses" — eliminate all enemies in a single encounter without being detected

• "Scavenger" — collect 50 crafting materials in one district

• "Shortcut Master" — unlock 10 shortcuts across the game

• "Overkill" — deal 500 damage in a single hit

• "Survivor" — complete the game on the highest difficulty

The "Shortcut Master" trophy ties directly into the side quest system because many shortcuts are locked behind optional case completions. Each district has two to three shortcuts that require solving a case to unlock, and these shortcuts often lead to safe rooms with workbenches and supply caches. Our complete gameplay guide covers the shortcut mechanics and how they interconnect with the main story progression.

Optimal Case Completion Order and Route Planning

Not all optional cases are created equal, and the order you complete them significantly impacts your survival odds in later districts. For instance, tackling the Warehouse Arson case early not only yields the Revolver blueprint—a critical upgrade for dealing with Dagon-spawned melee enemies—but also unlocks a safe route through the Burning Wharf that bypasses two ambush points. Conversely, delaying the Cryptic Broadcast side quest until after Chapter 3 forces you to backtrack through the Flooded Subway, where resource caches are already depleted. This section provides a recommended route that prioritizes reward quality while minimizing backtracking and resource waste, ensuring you secure key ammunition stocks and Medkits before the difficulty spike in the Old Town district.

District-by-District Priority

The Saint Mary's Hospital district should be completed in full before advancing to the Fish Market because the Drowned Ledger case provides weapon parts that make early combat viable. The hospital also contains two safe rooms and a workbench, making it the ideal base of operations for the opening hours.

The Fish Market district is where the game's difficulty spikes, and the SMG ammo recipe from Wharf Rats becomes essential because Deep Ones swarm in groups that the handgun cannot handle efficiently. Community testing suggests that players who complete Wharf Rats before entering the market's lower levels save an average of 15% more ammunition compared to those who skip it.

The Docks and Harbor districts are best tackled back-to-back because they share a connected underwater network that requires the diving upgrade from the main story. The Salt and Sorrow case in the Docks provides a rare melee weapon that deals bonus damage to corrupted enemies, which appear frequently in the Harbor district's final areas.

Resource Management While Questing

Side quests consume resources, and you need to budget carefully to avoid running dry mid-case. Each optional case typically requires 10-15 handgun rounds or 5-8 shotgun shells, plus medical supplies for healing. The crafting system allows you to convert found materials into ammunition, but the recipes must be discovered through exploration or case rewards.

• Ammo conservation — use melee attacks on single enemies to save bullets

• Medical supply priority — save medkits for boss encounters, not random fights

• Material hoarding — collect every crafting material you find, even if you don't need it yet

• Safe room usage — return to safe rooms to restock and save before starting a new case

• Shortcut awareness — unlocked shortcuts reduce travel time and resource consumption

The difficulty guide for The Sinking City 2 recommends playing on normal difficulty for your first completionist run because the higher difficulties reduce resource drops by 25%, making side quests significantly harder to complete without extensive farming. If you are attempting the "Survivor" trophy on the hardest difficulty, plan for 20+ hours of playtime and expect to die frequently in optional cases.

Advanced Strategies for Trophy Hunting Efficiency

Once you understand the case system and achievement requirements, you can optimize your playthrough to minimize replay time. This section covers advanced techniques that experienced players use to complete everything in a single run—most critically, the "Mind Palace" deduction mechanic, where failing to link the correct clue fragments to a case's core conclusion can permanently lock you out of the "Master Detective" trophy, forcing a New Game+ cycle. By prioritizing the "Witness Testimony" side cases (which have a 48-hour in-game expiry after their initial trigger) and saving the "Museum Heist" optional case for after you acquire the "Diving Suit" upgrade (required to reach the flooded basement), you can sequence your exploration to avoid backtracking through the city's infested districts, cutting roughly 6–8 hours of travel time from a standard completionist run.

Save Management and Backup Strategy

The game uses a manual save system with limited slots, and smart save management is crucial for trophy hunting. Before starting any optional case, create a dedicated save file so you can reload if you miss a specific achievement condition. The "No Witnesses" achievement, for example, requires a perfect stealth run through an entire encounter, and reloading is far faster than restarting the case.

The collectible tracking system in the game's journal helps you identify which memory fragments and journal entries you are missing per district. Check this screen before advancing the main story, because some collectibles become inaccessible after story progression locks certain areas.

Speed Optimization for New Game Plus

The Sinking City 2 does not feature a traditional New Game Plus mode, but the game does allow you to carry over weapon upgrades and safe combinations into a second playthrough if you complete the "Completionist" achievement. This makes the second run significantly faster because you can skip optional cases and focus purely on story achievements.

• Weapon upgrades persist — your fully upgraded arsenal carries over

• Safe combinations remain unlocked — no need to re-solve puzzles

• Crafting recipes carry over — ammo economy is much easier

• Collectibles reset — memory fragments and journal entries must be recollected

• Achievements re-earnable — most trophies can be earned again on the second run

The "Archivist" achievement is the most time-consuming because it requires collecting every journal entry, and several entries are hidden in optional case locations that are easy to miss. Use the journal screen to track which entries you have found per district, and consult community maps if you are stuck on the final few.

Frequently Asked Questions

How many side quests are in The Sinking City 2?

There are 14 optional cases spread across five districts, with two to three cases available per district. Each case takes between 30 and 75 minutes to complete depending on your familiarity with the puzzle mechanics and combat system. The total side content adds roughly 8-10 hours to a standard playthrough.

What is the best reward from optional cases?

The Lighthouse Keeper case in the Harbor District provides the best reward: a full armor upgrade that reduces all incoming damage by 20%. This upgrade is essential for the final chapters because enemy damage scales significantly, and no other source provides this level of protection.

Can I complete side quests after finishing the main story?

No, the game does not offer post-game exploration or chapter select. Once you trigger the final mission, all unfinished optional cases become permanently locked. This is why the "Completionist" achievement requires completing every case before the point of no return.

Do side quests affect the ending?

Side quests do not change the main ending, but they do unlock additional epilogue scenes that provide closure for side characters. The "Completionist" achievement unlocks a special post-credits scene that hints at the game's DLC direction, making it worth the effort for lore enthusiasts.

What is the hardest achievement to unlock?

The "Archivist" achievement is the hardest because it requires collecting all journal entries, and several are hidden behind optional cases that require specific choices during investigations. Missing a single entry forces a full second playthrough, making it the most punishing trophy in the game.