Kefir’s “Last Day on Earth” Retargeting Case Study

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Kefir! Intro

Kefir! is a game development studio famous for its hits Last Day on Earth, Grim Soul, Turyaga, Metro 2033, Eastern Front, and others. Their flagship projects are at the top of the charts in different countries around the world, with over a quarter of a billion downloads. They make games because they are gamers. They set challenging tasks and create games they’d like to play themselves. Intro is a tech product company driving mobile user acquisition for brands and app developers, operating world-wide and focusing on the US, KR, JP, RU, SEA, and IN markets. Using our proprietary bidder and machine-learning algorithms, we offer transparent, performance-based, highly-targeted UA, and retargeting solutions. strives to be more than just a vendor for its partners, but a partner that helps generate actual value, growth, and broad marketing insights that can be used across channels.

Campaign Goals worked together with Kefir! on their leading title, “Last Day on Earth,” on both platforms on a retargeting campaign in the US, DE, UK, CA, and KR, aiming to re-engage dormant users, introduce them to fresh content, and maximize their IAP revenue.


Our proprietary programmatic DSP is integrated with all major SSPs and can process more than 500,000 QPS of in-app inventory. We apply user-level targeting using our machine-learning algorithms, based on real-time request data and aggregated data from our DMP, to run effective UA  and retargeting campaigns. This infrastructure, designed to allow us to focus on user behavior, rather than just ad placements, enables us to help mobile app developers, such as Kefir!, to reach the most relevant users at the most opportune time. 

When we started running retargeting campaigns for Kefir’s “Last Day on Earth”, establishing which users should be targeted was simple thanks to Kefir’s team experience, and simple to digest on our backend thanks to our integration with Appsflyer’s Audience feature. The integration allowed us to expedite our timeline and get things up and running quickly by digesting the pre-defined, dynamic audiences automatically, which left us with the challenge of targeting these users effectively.

Our initial approach was sampling their reaction to ads in various points in their sessions in an abundance of different placements. Following a quick exploration run of a week, we established the targeting models (including hundreds of different sessions, user-behavior, and context related features) for each country and creative type, allowing us to decrease the cost per engagement rapidly. 

Then, our machine learning models gradually learned the patterns of the users that turned back active and made purchases within their first session back, which allowed us to target the other users in similar scenarios and eventually resulted in beating the defined KPIs.

CPA results:  The CPA goal was met on week 3, and continued on an overall positive trend, eventually leading to CPA 50% below the goal.
The CPA goal was met on week 3, and continued on an overall positive trend, eventually leading to CPA 50% below the goal.
D30 ROAS results: The ROAS goal actually set for D60, was beat on D30 starting from week two, and eventually reaching over double the target.
The ROAS goal actually set for D60, was beat on D30 starting from week two, and eventually reaching over double the target.


  • CPA goal beat in the second week.
  • D60 ROAS goal beat on D30.

 Olga Smirnova, UA Manager @ Kefir!

The team at had repeatedly shown that they are good at what they do and responded promptly to all changes. We were always confident that we would receive the necessary information with detailed explanations. A team of professionals and campaigns that achieved the required KPIs – what else could one ask for?

Olga Smirnova, UA Manager @ Kefir!
 Michael Zaitsev, Head of Customer Success at AppsFlyer

It’s always great to see our tools, like our Audiences feature used to drive effective marketing. We’re glad to facilitate the cooperation between advertisers like Kefir! and DSPs like and making their initial setup seamless, so that the focus could be on driving performance down the line.

Michael Zaitsev, Head of Customer Success @ AppsFlyer
Yan Reizin, Regional Manager, CIS @

We were quick to find a common language with our partners at Kefir! Running a retargeting campaign, we were able to achieve and exceed their KPIs, thanks to their data sharing and the transparency we had throughout the process.

Yan Reizin, Regional Manager, CIS @ 
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