Game overview
Marimo-VS-IAS: Our Friends
A 3D action where marimo moss ball fight to survive. Clear around 60 missions as you explore the lake, uncovering hidden items, information, side quests, and lurking threats… Use mission rewards and collected items to upgrade your marimo and take on powerful enemies!
- Last tracked players
- 0
- Recorded peak
- Unavailable
- 24-hour change
- Unavailable
Delayed observation · last tracked . Values marked unavailable are not estimated. Recorded peak is the highest player count observed by SteamIQHQ; earlier records may be outside our coverage.
About this game Read the full description
Evolve!
For our friends――

A 3D action game where marimo (lake balls) in Lake Akan—now part of the sea—fight for survival against various invasive alien species!
Master a variety of actions, mow down your enemies, and save your friend!
● Overview ●
Save Marimo!
Strengthen your marimo and wipe out the threats closing in on the Marimo――
Story Mode
Stage-based game mode.
Take on around 60 different missions, including defeating enemies, sabotaging their operations, and rescuing or defending your allies.
Challenge the hard-mode versions of each mission and aim to become the ultimate marimo!
Marimo Upgrades
Customize your marimo’s abilities freely using items obtained from rewards and exploration!
Adapting your upgrades to each situation is the key to overcoming powerful enemies and high-difficulty missions...
Field Exploration
Freely explore the lake to discover hidden items, information, side quests, and lurking dangers.
The environment may even change as the story progresses…
Training missions to help you get stronger
Even if you're not used to action games, you're welcome!
A training mode where you can learn the controls and rules while earning upgrade items.
Unravel the Mystery in an Optional Sub-Story
How did the Marimo survive in waters where the environment changed so drastically?
How did the lake end up becoming part of the sea?
Explore the lake and uncover the truth!

● Story ●
The marimo of Lake Akan once lived peaceful lives.
However, rising water temperatures and a lack of sunlight drastically reduced their numbers. With help from humans, they recovered and began to thrive again.
But after many years, the lake suddenly turned into seawater, wiping out much of its ecosystem. Invading species from the sea threatened the survivors, pushing the marimo to the brink of extinction.
Then, mysterious glowing particles appeared underwater, driving creatures into a frenzy… and granting new power to the remaining marimo.
(This story shares the same world and timeline as the previous title, "Marimo-VS-IAS," but can be fully enjoyed on its own.)
Media gallery 12 screenshots · 0 videos
Screenshots
Player activity
Concurrent players over the last 48 hours.
Price history
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System requirements Windows
Windows
Minimum
Minimum:- Requires a 64-bit processor and operating system
- OS: Windows 10
- Processor: Intel Core i7-9750H
- Memory: 16 GB RAM
- Graphics: NVIDIA GeForce GTX 1050 (Laptop)
- Storage: 5 GB available space
Recommended
Recommended:- Requires a 64-bit processor and operating system
- OS: Windows 11
- Processor: Intel Core i7‑12700
- Memory: 32 GB RAM
- Graphics: NVIDIA GeForce RTX 4070
- Storage: 10 GB available space
Game details Languages, features & support
- Publisher
- JoyPlot
- Brazilian rating
- l
- Steam Germany rating
- 0
- Achievements
- 26
- Controller support
- full
- Features
- Single-player, Steam Achievements, Full controller support, Camera Comfort, Custom Volume Controls, Adjustable Difficulty, Gamepad Recommended, #category_playable_at_your_own_pace, Playable without Timed Input, Save Anytime, Stereo Sound, Family Sharing
- Languages
- English, Japanese
- Website
- Official website ↗
- Support
- [email protected] Support site ↗
More analysis Activity patterns, updates & developer tools
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