← I Thalassa

Development Journey

30 monthly updates documenting the solo development of I Thalassa – The New World

The reworked I Thalassa main menu, with ship stats, save slots and the multiplayer host and join panel
Devlog 30

Multiplayer Matches, Ship Combat & Deep Sea Survival

Hi everyone, Manuel Hosseini here with Devlog #30 for I Thalassa. This month the game went online for real: multiplayer matches that play out from start to finish, manual ship combat with assisted aim, and survival that gets harder the deeper you dive.

  • Multiplayer matches from start to finish: spectator mode when you are eliminated, readable kick and quit messages, and a shared HUD that tells you who just left the game
  • Your own identity online, with duck colors tied to your Steam profile and a shipyard where you pick your ship before the match begins
  • Manual ship shooting with assisted aim and a new HUD crosshair, plus a laser that only fires once it is locked on target
  • New kamikaze bodyguard you throw from the inventory like a living mine, and an X-Ray vision button with cooldown to see through the dark
  • Oxygen now drains faster the deeper you dive, with new oxygen canisters and backpacks that change your speed and stats
  • Reworked main menu showing your ship stats, a simpler health bar, a dissolve effect when you die, and a whole new set of sounds for UI and missions
  • In-game bug report on F8 that sends a screenshot and logs straight to Discord, a new playtest code flow, and fixes to ship oxygen, homing weapons, bodyguards following you and overall performance
Several players swimming together around an underwater structure during a multiplayer session of I Thalassa
Devlog 29

Online Multiplayer, Story Arc Finale & Living Regions

Hi everyone, Manuel Hosseini here with Devlog #29 for I Thalassa. This was the biggest month so far: the game goes online with ship-vs-ship battles, the Shinoise story reaches its ending, and every region of the map now has its own look and identity.

  • Online multiplayer where you fight other players ship against ship, board their vessel, and bring your bodyguards and mounted sea animals into the fight
  • Battle royale mode: join a match, spawn far from everyone else, and be the last one alive to win
  • Steam invites and a Host/Join menu so you can jump into a session with your friends in a couple of clicks
  • The Shinoise story is complete with all 7 chapters in 8 languages, unlocked one after the other, plus a Lore Codex to re-read every discovery you made
  • Every region of the map now has its own environment, its name announced when you cross the border, and a minimap that follows you seamlessly from one region to the next
  • New compass with wind rose and coordinates, and a 3D arrow that points straight to your current objective
Devlog 28

Playable Duck, Story Fragments & Sea Currents

Hi everyone, Manuel Hosseini here with Devlog #28 for I Thalassa. This month was all about the new playable duck character, a story-fragment discovery system tied to Thalassa's lab, and rideable sea currents that carry you across the world.

  • New playable duck main character with full animations and a holographic dialog system
  • Story-fragment discovery that lets you collect document pieces and bring them to Thalassa's lab to uncover the mystery of Dr. Shinoise, with a drag-and-drop panel
  • Rideable sea currents you catch with a boost, complete with speed trails, tunnels, VFX, and a tutorial mission
  • New backpack jet booster item for faster underwater traversal
  • Building system control-panel tutorial plus fixes for build-mode toggling, placement, and flickering
  • First-time onboarding with inventory and controls tutorial dialogs
  • Playtest access gate with region check and Discord code, plus a new C#ese computer-language localization for the nerds
Devlog 27

Oxygen Survival, Refinery Modules & Enemy Escort Bodyguards

Hi everyone, Manuel Hosseini here with Devlog #27 for I Thalassa. This month was all about a new oxygen survival system powered by refinery modules, enemy escort bodyguards that protect their leader, and a big localization and virtual cursor pass.

  • New oxygen survival system with O2 zones, low-oxygen warnings, and a refiner prompt to top up before you run out
  • Refinery modules that convert raw items into power and oxygen, with dedicated UI for O2 and resource levels
  • Enemy escort bodyguards that guard their leader, with tuned health and a fix for shooting before acquisition
  • New oxygen and refiner-module missions hooked into the existing objective system
  • Player boost stamina meter, plus ship heal and fuel VFX for clearer feedback
  • Localization pass covering inventories, build modules, refiner, oxygen generator, and ship configurations with new tooltips
  • Virtual cursor fixed across all screen resolutions, with panel toggle exclusivity and build-mode UI fixes
Devlog 26

Gamepad Support, Trading UI & Fleet Save System

Hi everyone, Manuel Hosseini here with Devlog #26 for I Thalassa. This month was all about full gamepad cursor support, a unified UI panel system with shared trading, and a fleet save system that remembers every ship you own.

  • Gamepad cursor support across the main menu and in-game UI, with reduced thruster rumble feedback
  • New C and Z keybindings to quickly toggle the inventory and trading panels
  • UI Panel Manager with an exclusive slot so inventory and trading never open at the same time
  • Trading UI rebuilt as a scene-resident singleton shared by all NPC traders, freezing player movement while open
  • Fleet save system that persists every owned ship's position, fuel, and health across sessions
  • Sea animal riding refined with smoother controls, plus jellyfish attack and compass bug fixes
  • New weapons-item mission, a collectible document, and polished boost effects, environment, and main menu visuals
Devlog 25

Save System, Enemy Sentinels & Bodyguard Ships

Hi everyone, Manuel Hosseini here with Devlog #25 for I Thalassa. This month was all about a full save system with 3 slots, GPU-instanced enemy sentinel waves, and bodyguard capsule ships with swim-to-board recruitment.

  • Save system with 3 slots and ISaveable persistence for inventory, economy, missions, and build modules
  • Checkpoint interactable to save the active slot with session autosave and translated feedback in 6 languages
  • Enemy sentinels refactored to GPU-instanced manager with group FSM, wave loop, and dissolve shader on death
  • Bodyguard capsule ships with ship-driven controller, swim-to-board behavior, anchor system, and entry dialog VFX
  • New defeat enemy wave mission with compass target suggestion and per-group separation logic
  • Audio refactor with dedicated 2D AudioSource for UI sounds and spatial weapon SFX routed through AudioManager
  • Game Over screen with final explosion VFX, projectile rock impacts, refactored debris variants, and muzzle flash effects
Devlog 24

Mission System, Localization & Inventory Overhaul

Hi everyone, Manuel Hosseini here with Devlog #24 for I Thalassa. This month was all about building a full mission system with 10 unique objectives, expanding localization to five languages including Japanese, Russian, and Chinese, and overhauling the inventory with discovery slots and tabbed navigation.

  • Full mission system with 10 unique objectives hooked into combat, building, fishing, and exploration
  • Localization expanded to Russian, Japanese, and Simplified Chinese with Noto Sans CJK fallback fonts
  • Auto-detect OS language on first launch with English fallback and CSV sync tool for phrase management
  • Inventory overhaul with discovery slots, upgrade system, and tabbed sections for missions, discoveries, and help
  • Depth tracking HUD displaying depth in feet and pressure in PSI with surface breach detection
  • Jellyfish VFX migrated from LineRenderers to event-driven VFX Graph with improved chase and attack behavior
  • Turret controller with alternating randomized shots, food item healing system, and smoother camera movement
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