The Brief
Mimo Labs needed a booth activation for WhatsUp, Cosmote's youth brand, across its summer festival sponsorships: Release Athens, the Lex tour, Primer and Off The Hook. Festival-goers would step up to a 43-inch touchscreen set into a giant cassette tape, answer a few questions about how they live, and walk away with their own AI-generated song and a shot at a prize.
The song had to be theirs: their vibe, their genre, their motto sung back at them in Greek. A QR code on a physical cassette would take it home with them.
The Challenge
The brief landed on 4 June. The quote was approved on Sunday 7 June. The first festival was Saturday 13 June. That left five working days to design the flow, generate music that sounded right, and ship it.
AI music is slow and unpredictable. In testing, the first model mangled Greek syllables, and a song that mispronounces someone's motto in front of a queue is the brand's problem. Two days before go-live the agency asked for Suno instead, which has no official API.
Then the tour itself. 28 dates, some overlapping, each with a different line-up. A rap artist on Saturday meant rap only. A metal band on Monday meant metal only. One event needed English lyrics. Each date had its own prize pool.
What I Built
- Drag-and-drop on a cassette. Answers are dragged onto the tape graphic, with no free text beyond an optional one-line motto. Nobody could steer the AI off-brand.
- Lyrics first, then music. A language model writes brand-accurate Greek lyrics from the answers and keeps the motto word for word. Only then does the music model sing them.
- Swappable providers. Suno was integrated in one evening through a third-party API, with the original model on fal.ai as an automatic fallback. Each provider lives in its own module so the switch was a change request, not a rebuild.
- One link per event. Every festival date got its own URL that fixed the genre, set the language and scoped the prizes. 28 dates ran from one deployment.
- QR to a listening page. Each entry gets a serial number and a QR code to a mobile player, printed onto the physical cassette and emailed as a link.
- Admin panel. Prize quantities and odds typed in per event, a live QR sheet for the print team, submission exports and one entry per email address.
Stack: SvelteKit, Supabase, Vercel, Suno with Minimax Music on fal.ai as fallback, Groq, Resend
Go-Live
The test link went to the agency on Thursday 11 June. Feedback came back within the hour: drag and drop instead of taps, a play-again button, one genre to replace. All of it shipped the same day, and Suno went in that night. Friday brought a fix to outbound email and a free-text motto field. Saturday the booth opened at the Lex tour, and Monday it was at Release Athens.
Christos at the agency wrote back: "Client loved the WhatsUp game."
The Outcome
The booth cut 2,500+ demo tapes across 28 festival dates between 13 June and 19 September. After the first weekend, the only changes were a prompt tweak to make the motto land harder in the lyrics and two small admin refinements requested by the team. The agency did not need to raise a production issue for the rest of the run.
Why It Worked
Constrained inputs. The prompt is built from fixed answer fragments plus a short motto, so the output stayed on-brand without anyone reviewing songs.
Providers behind an interface. When the client wanted Suno two days out, swapping it in took an evening, and the fallback meant a provider outage would not stop the queue.
Configuration in the database, not the code. Genres, languages and prizes per event were rows, so 28 dates meant 28 links rather than 28 deployments.
Admin tools the agency could run on their own. Prizes, QR codes and exports were self-serve from day one, so a three-month tour needed no one on call from the UK.