Amazon Underground said it has been experiencing “serious growth” when it comes to customers, with numbers up 870 per cent since launch, and said developers “are starting to take notice” of this.

Aaron Rubenson, director of Amazon Appstore (pictured), told Mobile World Live this growth can be attributed to expanding to new markets, focusing on providing “a great experience” for customers, and adding a number of popular apps including Monument Valley, Star Wars: Knights of the Old Republic and Cut the Rope: Magic.

He also said the fact that Underground is available on all Fire tablets helped to drive 461 per cent growth over the holiday season.

The company says new customers mean more engagement and more money for developers. Royalties paid to app makers have grown by more than 3600 per cent since launch, and 87 per cent of games deliver higher revenue compared with other app stores.

Underground pays developers for every minute a customer uses their app or game, instead of having to rely on charging customers for a download or for in-app items, explained Rubenson.

This means developers can immediately generate revenue from 100 per cent of their users, instead of the 2 to 5 per cent of users they would generate cash from using other models, while focusing on creating engaging experiences.

“Developers are able to monetise their customers over the entire lifecycle of their apps” rather than having to “design their game strategy around when customers level up or want more lives.  Now, they can simply design around fun game mechanics and they will know that their app or game will make money,” Rubenson explained.

Underground has some impressive stats to back this up. In January, royalties paid out to developers across all of Amazon Underground grew 50 per cent month-over-month.

What’s more, since launching Final Kick in Amazon Underground, publisher Kerad Games saw a 900 per cent increase in average monthly downloads. And at the end of 2015, Coffee Stain Studios made more revenue in Underground for its game Goat Simulator than they did on any other Android platform.

Rubenson’s advice to developers is to “try something new”.

“Most Android apps will work without any modifications in Amazon Underground, and some developers have chosen to optimise their game strategy and in-app items for Amazon Underground by rewarding customers with in-app items as they progress naturally through the game,” he said.

Developers interested in publishing apps and games in Amazon Underground need to submit their app via the Amazon Appstore Developer Portal and can test APKs for compatibility with Underground using an app testing service.

“Almost any type of app or game that requires either a paid download or in-app purchases, and is in another app store, is a good fit for Amazon Underground,” he said.

As for Underground’s future plans, Rubenson said “our goal remains the same, in that our customers are able to have fun in their favourite apps and games, without having to make the choice of whether they should spend money to download the game, to get more lives, complete a level more quickly or unlock more features”.