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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!
Price history tracked since Jul 7, 2026 · vs all tracked offers.
Based solely on tracked price history — not purchase advice.
Tracked since Jul 7, 2026.
Steam Train Fest ends
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!
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!
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.)
Lowest tracked price: €13.65 (Jul 7, 2026) · current best: €19.50.
100% positive reviews all-time.
Right now the cheapest offer for Marimo-VS-IAS: Our Friends is €19.50 at Steam. KingsPrice compares 1 offers from 1 stores — official stores and keyshops — and refreshes prices throughout the day.
The lowest price KingsPrice has tracked for Marimo-VS-IAS: Our Friends is €13.65 (recorded on Jul 7, 2026). This covers the stores and period we monitor — set a price alert to catch the next drop to that level.
Create a free price alert on this page and KingsPrice will email you when Marimo-VS-IAS: Our Friends drops below your chosen price. The biggest discounts usually appear during seasonal Steam sales and publisher promotions — the sale calendar on this page shows the next confirmed event.
