The Tower

Lore & Background

The planet the colonists crash upon is a layered world of rock, ice, gas pockets, and toxic sludge. There is no surface air to breathe, no clean water to drink, and the ambient temperature can freeze or cook a creature in seconds. The Tower is born from this desperation: a narrow, vertical shaft carved upward through strata, each level sealed and pressurized, each room dedicated to a single survival function.

In the broader narrative of Oxygen Not Included, the colonists are sent to this world by an off-screen Command Center that issues tasks and expectations. The Tower is the colonists' answer to those demands—a self-sufficient engine of life in a place that offers none. As the colony grows, the tower grows with it, new floors added as research unlocks new machines and new biomes reveal new resources.

The verticality is not merely aesthetic. In the game's physics, warm gases rise and cool gases sink; liquids flow downward and pool at the lowest available point. A well-designed tower uses these rules as tools, routing oxygen upward to living quarters, dumping waste heat into lower utility floors, and channeling water through gravity-fed pipes to wherever it is needed.

In Their Own Story

The airlock hisses shut behind Mara. She presses her palm flat against the cold metal wall of the third floor, feeling the faint vibration of the oxygen generator humming two levels below. Above her, the research lab glows amber, its screens flickering with half-finished blueprints. Below, the furnace roars, painting the rock ceiling in shades of orange.

She climbs. One step, two, three. The temperature shifts with every rung—warmer as she ascends, the waste heat from the water processor bleeding upward through the cracked floor plates. Her breath fogs in the thin air. She can smell the ozone tang of the generator, the faint sweetness of the food processor's output two floors up.

At the top, the command center's screen blinks its next task. She reads it, exhales, and begins to climb back down. There is always more to build. There is always another floor to seal, another pipe to route, another colonist to keep breathing in the dark.

Reader's Guide

A tower-style colony in Oxygen Not Included is built vertically through the planet's cross-section, typically 5 to 12 floors high, each dedicated to a specific function. The narrative purpose is self-sufficiency: the player must generate oxygen, process water, cook food, manage heat, and produce electricity—all within a narrow footprint.

Key structural choices include placing heat-generating machines (furnaces, water processors) on lower floors so waste heat rises harmlessly, while living quarters and the research lab sit higher where the air is cooler. Oxygen generators are often placed mid-tower, with the generated gas routed upward to residential rooms. Water is typically processed at a mid-level and piped downward by gravity to sinks and toilets.

The interface with the player's broader base is the airlock and the elevator (or ladder) shaft running the tower's core. Research unlocks are the pacing mechanism: each new machine or tool justifies adding another floor. The design philosophy is constraint-driven—limited horizontal space forces vertical thinking, and the fluid/gas simulation rewards players who understand layering, pressure, and thermal convection.

Story significance: the tower is the colonists' declaration that they will survive. Every sealed door, every routed pipe, every balanced gas layer is a small act of defiance against a planet that wants them dead.

Did You Know?

• In Oxygen Not Included, warm gases naturally rise and cool gases sink, so a tower build can use this to separate toxic or hot exhaust from living areas without extra fans.
• The game's creatures are dual-gendered, and a healthy colony needs both males and females for reproduction to sustain the population over long playthroughs.
• The Command Center in ONI issues narrative tasks that guide the player's progression, effectively scripting the colony's growth from basic survival to advanced research.
• Liquid in ONI flows downward and pools at the lowest available surface, meaning a single misplaced water pipe can flood an entire lower floor if not contained.