MUTARIUM: Mutant Aquarium Defense

Feed them. They mutate. They fight.

MUTARIUM is a feed-and-defend roguelite. You never steer your fish — you decide what they eat, and the diet decides what they become. Meat grows teeth. Glow grows income. Ore grows armour and pulls aggro. Mix two feeds and you get something stranger.

Then the lab's escaped failures come back through the door, and whatever you raised is what you have to meet them with.

This demo holds the first two sectors: 28 waves, 4 bosses, 4 species — one of them still sealed for the full game. The facility goes deeper than that.

Wishlist the full game on Steam — planned release: November 2026.

Available in English, 한국어, 简体中文, 日本語, Русский, Español and Português (Brasil).

Played it? A 2-minute anonymous feedback form — every answer goes straight into development.

HOW TO PLAY

Click the water to drop the selected food. 1 / 2 / 3 switch food, E buys an egg, Q is the emergency chum (sector 2 only). Hold the click on an invader to fire — but read the wave forecast first, because some of them punish shooting. Coins are collected by moving the cursor over them, so your hand is always doing something.

CREDITS

Fish, invaders, bosses and tilesets: Elthen's Pixel Art Shop. Chapter 2 background: ansimuz, "Underwater Fantasy Pixel Art Environment". Fonts: Press Start 2P, VT323 and Chakra Petch (SIL OFL). Underwater ambience: Stormwave. Built in Godot 4.

AI DISCLOSURE

The visual art in this game was created with generative AI image and animation tools, then hand-edited, cleaned up and assembled by the developer. That artwork also appears in this page's cover image, screenshots and trailer. The code and the on-screen text were written with AI assistance (an LLM). AI was also used to translate the game's text into its six non-English languages. The game also uses licensed, human-made pixel-art asset packs from the sources credited above. All audio is human-made and licensed — no generative AI was used for any music or sound. No AI runs while you play — everything is generated ahead of time and reviewed by the developer before it ships.