About the project
About Aux Battles
Aux Battles is a free multiplayer music game built by Emilis, a solo developer, and launched on 9 April 2026. Friends join a room with a four-letter code, answer a prompt with one song, and rate each other's picks blind. There is no account, no download and no paid tier.
Why does Aux Battles exist?
To settle an argument. My friends and I played aux battles for years before any of this existed: someone picks a theme, everyone writes prompts on a literal notepad, we draw one at random, and the battles start. It works, and it produces the same argument every single time, because ratings shouted across a room do not average cleanly and whoever is hosting ends up doing the arithmetic in their head while everyone talks over them.
So I went looking for an app to handle the boring part: collect songs, collect votes, add them up. Every one I found wanted something first. An account, a login, a "create your free workspace" screen standing between me and a game that is supposed to start the second somebody says "let's do an aux battle." For a party game, that is disqualifying. The full story is in the first devlog post.
Who builds it?
One person. I am Emilis, and I write every line of this, from the game itself to the prompt library to the page you are reading. There is no team, no company and no funding behind it. The whole build is documented publicly, week by week, in the devlog, including the parts that went badly: an inline Spotify embed that played at full volume with no way to turn it down, shipped and deleted the same afternoon, is in there along with everything else.
The source is public at github.com/EmilisMi/AuxBattles, and you can reach me at mikalajunas.emilis@gmail.com. If something on this site is wrong, that is the address to tell me at.
How is it built?
React and TypeScript in the browser, Supabase for the database and the realtime updates, Vercel for hosting. The unusual part is that there is no authoritative game server: every player's browser subscribes to the same database rows and reacts to changes, so a room stays in lockstep without anything running between rounds. That is what makes a free, no-account party game affordable to keep online, and it is why room data is wiped after 24 hours rather than kept. See the privacy policy for exactly what is stored and for how long.
How many people have played?
These are real counts from the database, refreshed on every build, not rounded marketing numbers. The prompt library is hand-written and now runs to 3,505 prompts across 16 themes.
- 3,669
- Rooms played
- 3,848
- Players
- 5,284
- Songs submitted
About, answered
Who made Aux Battles?
Emilis, a solo developer. The project started on 9 April 2026 as a way to settle an argument that a group of friends had been having for years about who won the aux battle, and it has been built and run by one person since. The whole build is public in the devlog and the source is on GitHub.
Is Aux Battles a company?
No. It is one person and a side project. There is no company behind it, no funding, no team and no investors, which is also why there is nothing to sell you: the game is free because charging for it would mean building the account system it exists to avoid.
How does Aux Battles make money?
It does not. There are no ads, no paid tier, no premium features and nothing to subscribe to. Hosting is cheap because the game has no game server: the entire state of a room lives in a database that the players themselves write to, so a round costs a handful of database writes rather than a running process.
Why is there no login?
Because the founding constraint was that a friend should be able to join from their phone in about ten seconds without typing an email address into anything. Every app tried before this one failed that test, usually at a "create your free workspace" screen. Removing accounts is what makes the ten seconds possible, and every later decision has been made to protect it.
What is Aux Battles built on?
React and TypeScript in the browser, Supabase for the database and the realtime updates, and Vercel for hosting. There is deliberately no authoritative game server. Every player subscribes to the same database rows and reacts to changes, which is what keeps a room in sync without anything running between rounds.
How do I get in touch?
Email mikalajunas.emilis@gmail.com. That is the same address on the privacy policy and the terms, and it reaches the person who wrote this page. Bug reports, press questions, and "your comparison page has this wrong" corrections are all welcome.
Try the thing itself
It takes about ten seconds to start and about four minutes to play a round.
Start an Aux Battle