You’re betting that paying travel apps will win your business.

Changing people’s travel-buying habits is difficult, says Lorraine Sileo, senior analyst at travel research firm Focusright. “We know travelers are always looking for the lowest price, and that’s what they end up buying,” she says.

The travel industry spends heavily on advertising to win customer loyalty, Ms. Silio says. The ultimate goal of many companies today is to get travelers to use their apps and sign up directly with them instead of paying for referrals from Google. And while someone might visit a lot of websites to comparison shop, they’re not likely to download as many apps, she says.

Hopper is eschewing traditional advertising in favor of a rewards program designed to encourage people to visit the app even if they’re not planning a trip. Customers bought $50 million in rewards, vouchers and flash deals over the past 12 months, a company spokeswoman said. That number exceeds Hopper’s foreign marketing budget during that period.

Hopper surpassed Booking.com as the most downloaded travel booking app in the US last year.S

app, according to a report by analytics firm Sensor Tower. Although Expedia’s and Booking.com’s apps have outpaced Hoppers’ recent downloads, in 2016 It still holds that distinction in the first half of 2022.

The company is testing new programs that reward users for frequently opening the app, inviting others to the app, and even playing games.

The strategy is modeled on the success of e-commerce apps in Asia such as PinduoDuo.,

They use social and gaming features to fuel growth, says Frederic Lalonde, Hopper’s CEO and founder. Pinduoduo has integrated various features that reward people for spending time on the app.

In one PindoDuo game, one can water an imaginary fruit tree. After the tree is fully grown, the company sends the player a free fruit box.

Some of Hopper’s new features are already widely available. The app has a daily gift feature that rewards people every day they open the app. After seven consecutive days, customers will earn $10 in Carrot Cash, an in-app currency that rewards them with points or miles that can be used to reduce the cost of flights, hotels and car rentals. By the end of August, Hopper had made it available to 40% of users.

Other features that are still in the testing stages are more integrated. One allows users to earn Carrot Cash for completing tasks such as adding account information. Another one consists of small games similar to Pinduoduo’s tree water game.

Hopper users earn rewards for booking trips on the app. Carrot Cash currently cannot be combined with other offers such as vouchers and flash deals, a company spokeswoman says, and has a six-month expiry date.

Early findings indicate that games and rewards are working to keep people engaged with the Hopper app more often, Mr. Lalonde says.

In the case of travel-planning, one can open the hopper once a week, he says. Otherwise, they will interact with the app much less. Open rates for Hopper’s app are five to 10 times higher among people engaged with new games and features, he said.

“If I give you a good reason to start [the app] You start every day, every day,” says Mr. Lalonde. And you have no reason to launch a travel app every day.

Other travel companies are testing similar features. India-based Oyo launched games on its mobile app earlier this year. IHG Hotels & Resorts has partnered with mobile-gaming platform Playstudios. Members of the IHG loyalty program can earn points by playing mobile games and then redeem the points at discounted rates at IHG hotels.

Jonathan Barsky, an associate professor of management at the University of San Francisco, suggests that these features can be attractive to social casinos—apps or games that feature casino-like games but don’t involve real money wagering. Social casinos have around 80 million daily active users worldwide, he said. Popular examples include Big Fish Casino and Slotomania.

Chiazam Mbelu, 29, of Los Angeles, likes the Hopper app because it’s easy to use and allows her to track flight prices. She used Carrot Cash to save money on flights in the past, which she said was easy to do. But the way the app displayed Carrot cash and vouchers was confusing, she says.

Carrot Cash is stored in wallets and includes vouchers and discounts that can only be used on certain purchases, such as hotels or car rentals. When you open the app wallet, it differentiates between the two categories, although it combines the two sizes to give a total size. Sometimes Ms Mbulu says they think they will get more carrot cash than they actually do. (Ms Mbelu, a spokeswoman for Hopper, said they may have confused the two sizes.)

Ms. Mbelu said she is not one of the beta testers for Hopper’s new features, but she will give them a go. “Flight tickets are so expensive these days that any discount is worth it,” she says.

Write to Jacob Passy at jacob.passy@wsj.com