Dwarf Fortress: 16 years free on donations, then $7.2M in one Steam month

Brothers Tarn and Zach Adams spent two decades on Dwarf Fortress, a procedurally generated fantasy fortress simulation with deliberately crude ASCII graphics. From its first public release in 2006 the game was freeware, paid for entirely by fan donations, with the pair running on a modest independent income.

Build an unfathomably deep ASCII simulation, give it away free for 16 years funded by donations, then sell a polished premium edition — trust pays out $7.2M in a month.

On December 6, 2022, they launched a premium Steam edition with new graphics, UI and sound, published with Kitfox Games. It sold about 160,000 copies in 24 hours and nearly 500,000 by the end of the month, while the free Classic version stayed available on the Bay 12 site.

January 2023 brought $7,230,123 in revenue — roughly 44 times Bay 12's entire 2022 income of $164,666, and more than the brothers had earned from the game across the previous 15 years combined ($1,212,562).

Bay 12 Games' Dwarf Fortress, built by brothers Tarn and Zach Adams, is one of the most ambitious simulations ever made — a procedurally generated fantasy world whose fortresses, histories and disasters are generated rather than scripted. From its first release in 2006 it was freeware with ASCII graphics, funded entirely by fan donations.

The donation model worked for years but kept the pair on a small income: between 2007 and 2022 the game earned them about $1.2 million in total, and the whole of 2022 brought in $164,666. In December 2022 they released a premium Steam edition with new graphics, UI and sound, published with Kitfox Games, while keeping the free Classic version available.

The launch sold about 160,000 copies in 24 hours and nearly 500,000 by the end of December. In January 2023 the game grossed $7,230,123 — roughly 44 times the studio's entire 2022 income, and more than the previous 15 years combined. The brothers said the money solved the health and retirement concerns that trouble independent developers.

The game was given away for 16 years, so the audience had a deep, trusting relationship before a single dollar was asked of them at launch.

Donations kept the project alive without a publisher, letting the brothers stay true to an uncompromising design.

The premium edition added what freeware could not — graphics, UI and sound — so the paid product was an upgrade, not a paywall.

A tiny niche audience of devoted fans out-earned mass-market ad models, proving depth beats reach.

Freeware funded by fans is not charity — it is a 16-year trust deposit; when you finally charge, the audience that loved your work pays back at launch, not through ads.

The windfall let Bay 12 hire more programmers — the project had been run almost entirely by Tarn — and secure the game's future. The free Classic edition remains downloadable, development continues with regular monthly updates, and the December 2022 release became the canonical example of a donation-funded freeware project converting its audience into a commercial hit.