Ice

Lore & Background

In the world of Oxygen Not Included, the planet's shallow crust holds pockets of water that have settled into a crystalline lattice, locked in place by the ambient cold of the upper strata. These ice deposits are not the product of any single storm or season; they are simply water that never found enough warmth to shift back to liquid. They glitter faintly in the dim bioluminescent light that filters down from above, and their pale blue-white hue makes them easy to spot against the darker soils and rocks surrounding them.

For the Duplicants, ice carries a quiet poetry. It is the same substance they drink from a tank, the same substance that rises as steam from a heater, yet here it stands still, solid, patient. A Duplicant swinging a pickaxe at an ice tile feels the familiar resistance of solid matter, but the shards that fly off are lighter, cooler, and they dissolve on the tongue if one is careless. Colonies that learn to respect this duality—solid enough to build with, fragile enough to vanish in a warm room—find ice to be a resource that rewards foresight.

Over the course of a long colony, ice becomes a symbol of the game's deeper theme: nothing is fixed. The wall you built is the water you will drink. The water you drank was the steam that fogged your visor. The steam was the ice you left in the upper strata. In a world of Duplicants, water is a cycle, and ice is simply the pause between breaths.

In Their Own Story

The pickaxe bit in with a sound like a knuckle cracking. Kael watched the pale shard tumble free and catch the faint glow of the overhead lamp, turning it into a brief, cold star. Around her, the upper strata hummed with the low vibration of the colony's heaters three levels down, and she could feel the warmth creeping up through the rock, patient as a tide.

She set the ice block on the workbench. It sat there, innocent and still, while the ambient temperature ticked upward on the readout. 0.1. 0.3. 0.7. A thin bead of condensation formed on its surface, then a second, then a slow, glistening trickle ran down its face like a tear.

Kael wiped her brow. Somewhere below, a Duplicant was already filling a tank, already breathing easier. The ice was gone. The water was not. It never was. It just changed its mind about being still.

Reader's Guide

Position in the cross-section: Ice deposits are concentrated in the upper strata of the planetary cross-section, typically in the first several layers below the surface. They appear as scattered tiles among soil, rock, and lighter mineral deposits. You will encounter them early, often within the first few minutes of a new colony, making them one of the most accessible solid resources.

Physical properties: Ice is a solid, non-flammable material with a melting point of 0 °C (32 °F). It is less dense than liquid water, meaning it will float on the surface of a water pool rather than sink. As a solid, it can be placed as a structural building material, forming walls, floors, and ceilings. It does not conduct electricity and does not burn, making it a safe barrier material in the short term.

Processing and yields: Mining ice with a pickaxe yields ice blocks that can be stored, placed as building, or melted. Melting ice (by heating it above 0 °C, placing it near a heater, or using a water extractor) converts it into liquid water, which can then be stored in tanks, used for drinking, cooking, or as a byproduct of other processes.

Hazards: The primary hazard is thermal. If a colony's ambient temperature rises above 0 °C, any exposed ice will melt, producing free water that can flood corridors, short-circuit electronics, and create slippery surfaces. In a poorly ventilated or heated area, a wall of ice can become a wall of water within minutes. Additionally, because ice is structurally weaker than stone or metal, it is not ideal for load-bearing construction in a long-term colony. Plan to replace ice structures with more durable materials once your colony stabilizes.

Did You Know?

• Ice in Oxygen Not Included floats on liquid water because it is less dense, just like real-world ice—a small detail that can turn a flooded corridor into a floating obstacle course for your Duplicants.
• Because ice is non-flammable and solid, it can serve as a quick, temporary firebreak in the early game, buying precious seconds before a blaze spreads through a wooden or paper-adjacent section of the colony.
• The same water molecule that exists as ice in the upper strata, liquid in a tank, and steam in a vent is tracked as one continuous resource pool in the game's simulation, meaning melting ice never 'creates' water—it simp
• A Duplicant can mine an ice tile, carry the block to a warmer room, and watch it melt in their inventory area, releasing a small puddle of water right where they stand—a tiny, avoidable hazard that has ended more than on