Volkswagen turns a subway staircase into a piano — 66% more commuters take the stairs

Volkswagen Sweden wanted to promote its fuel-efficient BlueMotion line in an increasingly crowded eco-car market, at a time when traditional advertising was losing effectiveness. Its agency, DDB Stockholm, built the campaign on a single idea: people change their behavior more easily when the change is fun than when it is asked of them.

Replace the argument with the experience: make a stairwell play piano notes as people climb, so choosing the healthy option is fun enough to beat the escalator.

The Fun Theory launched in 2009 with viral experiments shot in Stockholm. In the flagship piece, the stairwell of Odenplan subway station was converted into a working piano — each step played a note as commuters climbed — placed next to the escalator so the choice was visible. A second video showed a 'world's deepest bin' that made dramatic falling sounds when trash was dropped, and a third turned a bottle bank into an arcade game. The films then fed a public contest inviting people to submit their own fun-theory experiments, with a €2,500 prize.

When the stairs were musical piano keys, the number of commuters who chose them over the escalator rose 66%, and the piano-stairs video passed 2.5 million views on YouTube within weeks of release. The campaign travelled as a viral phenomenon and was widely credited with demonstrating that behavior change can be engineered through enjoyment rather than instruction — a reference point later used across public-health and sustainability work.

In 2009 Volkswagen Sweden was promoting its BlueMotion fuel-efficiency line in an increasingly crowded eco-car market, and DDB Stockholm concluded that traditional green advertising was not enough. The agency's deputy manager Lars Axelsson said the brand needed a more innovative approach to draw attention to BlueMotion, and the result was The Fun Theory: fun is the easiest way to change people's behavior for the better.

The campaign's first phase was a set of viral experiments shot in Stockholm. The most famous converted the stairwell of Odenplan subway station into a working piano, with each step playing a note as commuters climbed — deliberately placed beside an escalator so the choice between them was explicit. Companion films showed a trash bin that made dramatic 'deepest bin' sounds when used, and a bottle bank turned into an arcade game. A contest phase then invited the public to submit their own fun-theory experiments for a €2,500 prize.

The results made the idea famous: when the stairs played music, 66% more commuters chose them over the escalator, and the piano-stairs video passed 2.5 million views on YouTube within weeks. CNN covered the experiments as ingenious ways to get people to do the right thing while having fun, and The Fun Theory became a frequently cited proof that enjoyment can outperform instruction in changing everyday behavior.

Making the stairs musical changed the decision in the moment, at the exact point where the escalator normally wins.

Placing the piano stairs beside the escalator made the better choice visibly more fun instead of merely more virtuous.

Viral films let the idea travel without paid media, earning millions of views on YouTube.

The contest turned the audience into co-creators, extending one campaign into a proof of the theory itself.

When the goal is behavior change, don't argue with people — redesign the choice so the better option is also the more fun one, and the escalator loses by itself.

The Fun Theory videos became a global viral phenomenon in 2009 and were followed by more experiments in the same series, including the bottle-bank arcade game. The piano-stairs idea was cited for years afterward in discussions of behavioral design and 'nudge' campaigns, and the 66% figure became a standard example of how making an activity fun can change how people choose — even when both options are right next to each other.