What broke when Doom went online on December 10, 1993?
id Software released Doom as shareware on December 10, 1993, uploading the free first episode to an FTP server at the University of Wisconsin. The upload took more than one attempt, because so many people were already sitting on the server waiting for the file to appear.
The demand did not stop at one campus. A Carnegie Mellon Computing Services notice posted within hours of the release said the game was "bringing the campus network to a halt," and warned that administrators might disconnect the machines of anyone who kept playing.
The cause was technical rather than moral. The first release of Doom used broadcast packets for its network play, so one four-player match degraded performance for every computer on the same segment, whether or not those computers were running the game. Mid-December is also finals season at American universities, which is why the notices from that week read the way they do.
The registered version, with all three episodes, went out by mail order from the same week. The free first episode kept spreading on its own, through bulletin board systems, university file servers and floppy disks passed hand to hand.
What could the Doom engine do that Wolfenstein 3D could not?
Wolfenstein 3D, id Software's previous shooter, drew a world of flat floors, uniform ceiling heights and walls that met at right angles. It read as a maze because it was one.
Doom broke all three limits. Rooms could sit at different heights, with stairs and lifts between them. Floors and ceilings carried textures instead of staying blank. Light levels changed from room to room and could flicker, which is most of the reason the game frightens people rather than just occupying them.
John Carmack got there with binary space partitioning, a technique that chops a level into a tree of sub-spaces so the renderer only draws what the player can actually see. The levels are not true three-dimensional geometry. They are a two-dimensional map carrying height information, which is why the original engine cannot put one room directly above another.
The payoff was a game that ran at speed on an ordinary office PC of the period, with no graphics acceleration of any kind in the machine. Nothing else on a desktop moved like that, and the gap between Doom and everything around it on the shelf was obvious within about ten seconds of play.
How did a free game make $100,000 a day?
Shareware was not new in 1993. id Software had already used it for Commander Keen and Wolfenstein 3D, distributed through Apogee Software. What changed with Doom is that id cut out the publisher and took the orders itself.
The structure was simple. Episode one, "Knee-Deep in the Dead," was free to copy and free to pass around. Episodes two and three cost $40 plus shipping, ordered direct from id Software by mail or phone.
David Kushner's book Masters of Doom, published in 2003, reports that shareware registrations brought in $100,000 a day in the stretch right after release. With no retail chain and no publisher in the middle, most of each $40 order stayed with a company that had fewer than a dozen people in it.
The long tail was just as strange. PC Data, which tracked United States software sales, counted 1.36 million units and $8.74 million in revenue for the Doom shareware edition alone by April 1998. That was enough to rank it the fourth best-selling computer game in the country for the period from January 1993 to April 1998, five years after it came out.
How did deathmatch turn PC gaming into a competition?
Doom shipped with two multiplayer modes: cooperative play, and a free-for-all that John Romero named deathmatch. Up to four players dropped into the same level and scored on kills. No teams, no objectives, no rounds.
That mode is why the campus notices exist at all. The Carnegie Mellon Computing Services notice of December 1993 was blunt about it: "Computing Services asks that all Doom players please do not play Doom in network-mode."
Off campus, deathmatch got people hauling desktop towers and CRT monitors into basements, offices and garages and taping network cable across the carpet. LAN parties existed in a small way before 1993. Doom is what turned them into a weekend habit with a packing list.
The line from there to modern competitive shooters is short. id Software's Quake took the same idea from the local network onto the internet, the Half-Life mod scene turned it into Counter-Strike, and the scoring language Romero coined is still the one every shooter uses.
Why does Doom still turn up on printers and pregnancy tests?
Two decisions made Doom outlive its hardware. The first was keeping the game's content in separate data files called WADs, so anyone could build new levels, textures and monsters without touching the engine. The second was releasing the engine's source code, which id Software later relicensed under the GNU General Public License.
Once the code was public and the licence permissive, porting it became a hobby with no ceiling. Doom has been rebuilt for graphing calculators, cash machines, digital cameras, office printers, car dashboards and a digital pregnancy test, although that last project swapped out the test's processor and screen and kept only the plastic shell.
The level scene never stopped either. Volunteer mappers have been shipping WADs continuously since the mid-1990s, and the official 2024 re-release ships with a browser that downloads community add-ons from inside the game, which is an unusual thing for a publisher to bless.
The joke now runs the other way. A new processor is not properly launched until somebody has made Doom run on it, and that test says more about the engine's size and portability than any benchmark does.
Is Doom still being made in 2026?
Yes, and the owner is Microsoft. Microsoft announced a deal to buy ZeniMax Media, the parent company of Bethesda Softworks and id Software, in September 2020 at $7.5 billion, and finalized the purchase on March 9, 2021. id Software is still the studio that builds the games.
The series is active rather than archived. id Software released Doom: The Dark Ages on May 15, 2025 for PC, Xbox Series X|S and PlayStation 5, and it went onto Game Pass the same day it went on sale.
The 1993 original is still sold, and not as a museum piece. Doom + Doom II arrived on August 8, 2024 for PC, PlayStation, Xbox and Nintendo Switch at $9.99, running on the KEX engine with crossplay, 4K support and the in-game mod browser. Anyone who already owned Doom or Doom II on a given platform got the new version as a free upgrade.
Where to find one today. Doom + Doom II lists at $9.99 and is discounted regularly, so the classic id Software catalogue on GOG is the cheapest honest route, and it is sold without DRM. If you would rather run an original MS-DOS copy you already own, the setup covered in running 90s PC games on Windows 11 handles it without buying anything.
Frequently Asked Questions
Who owns Doom now?
Microsoft owns Doom. The series belongs to id Software, which sits inside ZeniMax Media alongside the publisher Bethesda Softworks, and Microsoft completed its purchase of ZeniMax Media on March 9, 2021, in a deal announced in September 2020 at $7.5 billion. id Software remains the studio that develops new Doom games.
Can you still play the original Doom in 2026?
Yes. The 1993 original is sold as Doom + Doom II, released on August 8, 2024 for PC, PlayStation, Xbox and Nintendo Switch at $9.99, and that package bundles The Ultimate Doom, Doom II and several expansions. Free community source ports, built on the engine code that id Software released under the GNU General Public License, also run the original game on almost any modern computer.
How much money did Doom make?
Doom brought in roughly $100,000 a day in shareware registrations in the weeks after its release on December 10, 1993, according to David Kushner's Masters of Doom. By April 1998, PC Data counted 1.36 million units and $8.74 million in United States revenue for the Doom shareware edition alone, which excludes the boxed releases, the sequels and the money id Software made licensing its engine.