Open silentspacemarine.com, press Start Multiplayer or Play Solo, and play Doom with up to four players in your browser. Cloudflare compiled Chocolate Doom to WebAssembly and open-sourced it. The live demo preloads the Doom shareware data.
The original game
A nameless space marine, stationed on Mars, fights through the moons of Mars and then Hell against demons and possessed humans. The game was split into three episodes, and the first was given away free as shareware on December 10, 1993. It sold an estimated 3.5 million copies by 1999 and is widely credited as the father of first-person shooters.
Designed by John Romero, Tom Hall and Sandy Petersen. Programmed by John Carmack, John Romero and Dave Taylor. Music by Bobby Prince. Source released in 1997 under a non-commercial licence and under the GPL in 1999. Doom on Wikipedia
The browser version
The page at silentspacemarine.com is titled "WebSockets Wasm Doom" and says: "This is a WebAssembly Doom Port With Multiplayer support running on top of Cloudflare's Edge Network." It has two buttons, Start Multiplayer and Play Solo. It is the live demo for the Cloudflare blog post "Multiplayer Doom on Cloudflare Workers", written by Celso Martinho and published on May 18, 2021.
The port takes Chocolate Doom and compiles it to WebAssembly with Emscripten. Cloudflare wrote a new network module, net_websockets.c, to replace UDP with WebSockets. Each player connects to a message router on Cloudflare's edge, and each game session is a room backed by a Durable Object that forwards packets between players. The post says up to four can play.
On data: the post names doom1.wad as preloaded into the browser's virtual file system, and the repository README says to supply the shareware doom1.wad yourself since the repo does not include it. The code is open source: the WebAssembly port at cloudflare/doom-wasm (GPL-2.0) and the site and router at cloudflare/doom-workers.
| Method | Chocolate Doom compiled to WebAssembly with Emscripten |
|---|---|
| Networking | WebSockets through a Cloudflare Worker, one Durable Object per room |
| Players | Up to four |
| Game data | doom1.wad, preloaded in the live demo |
| Licence | GPL-2.0 (cloudflare/doom-wasm) |
How to play it
- Open silentspacemarine.com.
- Press Start Multiplayer to create a room, or Play Solo.
- On a phone, hide the browser toolbar for more room, as the page suggests.
Links
Source code
Questions
Can you play Doom multiplayer in a browser?
Yes. silentspacemarine.com runs multiplayer Doom in a browser tab for up to four players.
Is it recompiled or decompiled?
Neither: Doom's source has been open for decades. Cloudflare compiled the Chocolate Doom source port to WebAssembly. People search it as "Doom recompiled" for the same thing.
Do I need to own Doom?
The live demo preloads doom1.wad. If you build it yourself you supply the shareware doom1.wad.
How does the multiplayer work?
Players connect over WebSockets to a Cloudflare Worker, and each game is a room backed by a Durable Object that forwards packets.
Who made it?
Cloudflare, as an experiment. The blog post is by Celso Martinho.
Sources and coverage
Details checked 2026-10-08. Fan projects change fast; check the project page for the latest.