Furnace 23

Lore & Background

In the early days of Factorio, when the Electric Furnace was the absolute ceiling of smelting technology, a persistent question haunted the forums: 'What comes after?' Players, hungry for one more tier of industrial complexity, began speculating about a hypothetical next furnace. The number '23' stuck for reasons no one fully agrees on—some trace it to a forum post's post number, others to a random seed value, and still others simply to the aesthetic satisfaction of a specific two-digit number that felt 'just past the edge of the known.'

Over time, 'Furnace 23' became a kind of fan totem. It represented the community's collective desire for more progression depth, more research to chase, more ways to make a factory feel like it was still growing. Modders occasionally used it as a placeholder name in experimental smelting mods, and it appeared in fan-made tech-tree diagrams as a ghostly, dashed-outline box at the far right of the progression chart. It was never a promise from Wube Software; it was a wish projected onto the game's architecture. What makes the concept endure is that it captures something true about Factorio's design philosophy: the game is deliberately bounded, and the players' imagination is not. 'Furnace 23' is the space between the last researched technology and the infinite factory in your head. It is the hum you imagine a machine making that the developers never coded.

In Their Own Story

The night shift at the factory is quiet. You stand before the Electric Furnace, watching the orange glow pulse through its glass panels, and you think: this is the last one. There is no next box to check. No new research to queue. The smelting chain ends here, in this small rectangle of heat. You pull up the blueprint list. You scroll past the Stone, past the Steel, past the Electric. And there, in the margins of your mind, not in any save file, not in any mod pack—there is a shape. A slightly larger box. A faintly different glow, maybe blue-white instead of orange. You give it a number because numbers feel official. Twenty-three. It doesn't matter why twenty-three. You close the laptop. The factory hums on, perfectly sufficient, perfectly complete. But you keep the number. You keep it the way you keep the sound of the conveyor belts at 3 a.m., the particular rhythm that means *I built this, and it works, and I could build one more thing.* You never do. You don't need to. The furnace that isn't there is the one that keeps you coming back.

Reader's Guide

Furnace 23 does not exist in Factorio's base game, any official DLC, or any widely-adopted mod. There is no research cost, no prerequisite chain, and no unlock condition because it is a fan-imagined concept rather than a shipped technology. In the actual progression, smelting follows a clear three-tier path: the Stone Furnace (available from the start, no research required), the Steel Furnace (unlocked via the 'Steel Furnace' technology, requiring Steel and a prerequisite in the early tech tree), and the Electric Furnace (unlocked via the 'Electric Furnace' technology, requiring Steel, Electronic Circuits, and a position in the mid-game research chain). The Electric Furnace is the final smelting tier and remains so in all current versions. The 'Furnace 23' concept appears in community tech-tree diagrams as a speculative fourth tier. Fans have proposed that it might use a new energy source, have higher throughput, or require a previously-unseen material. None of these have been confirmed by Wube Software. For blueprint sharing, the game's save/share mechanic (Ctrl+B to copy a blueprint, Ctrl+V to paste, or uploading to the Factorio blueprint sharing platform) works identically for all three real furnaces. No community blueprint library contains a 'Furnace 23' item because the game's data files do not define it. Any mod that adds such an item would be entirely fan-made and outside official scope.

Did You Know?

• Factorio has exactly three furnace types—Stone, Steel, and Electric—and the Electric Furnace has remained the final smelting tier since the game's 1.0 release in 2020.
• The term 'Furnace 23' appears in fan forums and social media as a shorthand for 'the next thing that doesn't exist yet,' functioning more as a cultural meme than a specific design proposal.
• Factorio's blueprint system allows players to copy, paste, and share factory layouts, and the three real furnaces are all fully compatible with this system—no special handling is needed for any furnace tier.
• Wube Software has confirmed in community updates that the base game's technology tree is intentionally finite, meaning no fourth furnace tier is planned for the core experience.