Slime Castle: A brief case study in growing IAP revenue for a new project
When we first came across Slime Castle, we reached out to the developers directly. They shared their initial metrics with us, and it was clear the project had immense potential, even though it needed refinement. The studio had been in talks with several publishers before us, looking for someone who not only understood idle games but also believed in the game’s future and the team’s vision.
After we first tried the game, we didn’t hesitate — we immediately proposed running an LTV test. The existing metrics were promising enough to warrant jumping right in:
- Average retention: nearly 40%
- Total CPI: $0.28
At the time, R7 and especially R30 were harder to assess — not because the game lacked quality, but simply because it was such a fresh project with limited content.
But thanks to our experience, sometimes all it takes is one look at a game and a conversation with the developers to spot the potential. Especially if there are initial metrics to back that up. It’s not just about the numbers or visuals; it’s also about the team behind the project. The developers had a clear roadmap and vision for adding new content (that was very much needed), which immediately caught our attention.
We made a conscious decision not to micromanage the development process. If the team could build such a project on their own, they already had the expertise — we just wanted to help guide them in prioritizing updates and scaling up quickly for the best results.
The studio delivered the first iteration of the game at the end of December 2023. We began collaborating in February, and by May, we were purchasing traffic.
Over the next six months, Slime Castle generated more than $7 million in in-app revenue (plus several million from ads). In May, the IAP revenue was only $250,000, but by August, it had nearly quadrupled to $1.5 million and is still climbing. This growth defied the typical summer slowdown in IAP revenue, with boosts more often seen during winter.
Our biggest contribution to the success of Slime Castle was offering expertise in UA and budgeting. Without experience and analytics, it’s incredibly hard to balance the fear of losing everything with the desire to scale for higher earnings.
Rapid growth can sometimes lead to sharp declines, and teams may continue acquiring users out of sheer momentum, draining resources unnecessarily. Recognizing when to push further and when to pull back is a skill that only comes with experience.
Another key factor is knowing which features to prioritize. For many developers, implementing every idea can feel like a personal mission: “If we’ve thought of it, we need to build it.” But understanding the impact of each feature at the right time is often the strength of a publisher with hundreds of launches under their belt.
Casual games, especially those with long-term potential, present unique challenges in content, balance, and development compared to other genres. Successful projects like Slime Castle tend to build active communities eager for updates and new content. The game aligned perfectly with our focus on long-term operation and sustainable growth.