The archive · Consumer Apps · Product decision · 2020
Kosmi bets browser-streamed PS1 rooms revive couch co-op; HN gave it 676 points
Kosmi's PSX Party streams a host-run PS1 emulator over WebRTC so friends can couch co-op in a browser; the 2020-12-30 Show HN drew 676 points.
Kosmi
What the business is
Kosmi is a browser 'party' service where friends open a room to watch and play together with chat and video; PSX Party is its Playstation 1 mode, in which one participant runs the emulator in the browser and streams the screen while everyone else joins with controllers.
How it started
Kosmi, which a commenter described as 'just one guy', had already built snes.party; users in the PSX Party thread describe spending lockdown nights on it with partners and friends. On 2020-12-30 its builder, hauxir, posted PSX Party to Hacker News: the same browser-room model extended to a Playstation 1 emulator, with the emulator, ROMs and BIOS drawn from MAME and the Internet Archive's public PSX collection.
What happened
The Show HN drew 676 points and 171 comments. hauxir explained the architecture in the thread: one participant runs the emulator locally in the browser and streams the video, accepting inputs from the other room participants; one commenter called it the best engineering hack of the year. Praise came with scrutiny — a commenter reported a 0.5 to 1 second input delay on the NES version, others asked about gamepad mapping and the mediasoup client, and licensing questions surfaced over the MAME-based emulator (answered with a GPL fork, kosmigramma/mame) and over pulling ROMs from the Internet Archive.
No ending yet — it is still running.
Background
Kosmi's bet was that the browser room could replace the couch. The service, built by one person posting as hauxir, lets friends open a room with chat, voice and video; its earlier snes.party had already found its moment when commenters used it to stay connected through Covid lockdowns. PSX Party, launched on 2020-12-30, extended the same room to a Playstation 1 emulator running in the browser.
The architecture made every PS1 title a potential multiplayer game without writing netcode for it: one participant runs the emulator locally and streams the video over WebRTC, while the other players' controllers send inputs into the room. hauxir confirmed this design in the launch thread and pointed to MAME, the same emulator behind the Internet Archive's PSX collection, as the engine underneath.
Hacker News responded with 676 points and 171 comments, with one commenter calling it the best engineering hack of the year. The scrutiny was just as sharp: users reported input lag on the sibling NES party, asked about gamepad mapping and the mediasoup client, pressed the maker on GPL obligations for the MAME code, and questioned the legality of pulling ROMs and the BIOS from the Internet Archive.
As of 2026-09-05 the PSX Party page is still live — 'Free multiplayer PS1 retro gaming in your browser. No downloads, no plugins' — with the same create-a-room, load-a-ROM, play-together flow. The launch thread and this material record no revenue, funding or user figures, so the venture's scale is not documented here.
What has to be true
- The room was the wedge: Kosmi already had chat, voice and WebRTC plumbing, so each new console was a mode rather than a platform built from scratch.
- Host-streaming dodges per-game netcode: one browser runs the emulator and friends send buttons, so any PS1 title works without synchronizing emulator state.
- Lockdown gave the product its moment: commenters said snes.party nights kept partners and friends connected through quarantine apartness.
- The stack was deliberately grey — MAME code and Internet Archive ROMs — which is exactly where the thread's sharpest legal and technical objections landed.
What can be applied
A 676-point launch proves the hack, not the venture: latency, ROM licensing and GPL obligations decide whether streamed retro gaming is a business or a feature.
Aftermath
As of 2026-09-05 the PSX Party page is still live at psxparty.kosmi.io: 'Free multiplayer PS1 retro gaming in your browser. No downloads, no plugins — just instant co-op fun', with a create-a-room, load-a-ROM, play-together flow. The 2020 launch thread and this material record no revenue, funding or user numbers, and nothing here claims whether Kosmi is still run by one person.
Sources
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