After web searches, the next most likely way for people to find your tour is by searching in the Apple App Store or Google Play. This is more indirect - after all, before they find your specific tour, users have to discover and then install VoiceMap. But reviews of the app can help them get there, if they mention your tour.
The App Store and Google Play rank apps differently in different countries. The number one search result for "audio tours" displayed to users in the US and Australia isn't always the same, for example. VoiceMap already ranks highly for all sorts of generic searches in a wide range of countries - and it is actually the number one search result for "audio tours" in both countries at the time of this writing - but for searches that include the names of specific countries, cities or even neighbourhoods, it's impossible for us to cover everything in the app description and our choice of a few keywords.
That's where reviews come in: if they mention your tour, they'll greatly improve the chance of VoiceMap appearing in searches related to it. A search for "audio tour of vienna" is more likely to have VoiceMap up top, for example, if there is a review of the app that mentions The Heart of Vienna, our only tour there. In fact, reviews have an outsized influence on how both Apple and Google rank apps. Users pay close attention to them too, and it's easy to see how they might easily go on to buy your tour if they see a glowing review of it while browsing the App Store or Google Play.