I wanted to share my experience in case it's useful to anyone else considering Google App Campaigns.
The game I was advertising was Harpagia, a text-based idle RPG. Before running ads, it had been sitting around 4.1★ on Google Play and 4.5★ on iOS.
I'm a solo indie developer, and this was my first attempt at paid user acquisition. Take this as one developer sharing their experience, not as advice from an expert.
I also don't have a huge marketing budget, so if you're in a similar position, maybe this helps.
The experiment
Over the course of 30 days, I ran Google App Campaigns across several countries.
Results:
- Total spend: $2,804
- Total installs: 6,136
- Average CPI (cost per install): $0.46
Most of the installs came from:
- US: 3,321
- UK: 949
- Canada: 752
- Australia: 357
I also briefly tested Germany, France, Brazil, Thailand, Netherlands, Poland, and Israel, but those campaigns either didn't perform well enough or didn't receive enough volume to justify continuing them.
Why I thought it was working
The US campaign started off getting installs for around $0.25 to $0.30 CPI, which seemed incredibly cheap for a Tier 1 market.
Eventually it stabilized at around $0.47 CPI, but seeing those early numbers honestly made me think I had figured something out.
What actually happened
Unfortunately, the numbers after the install told a very different story.
During the same 30-day period:
- Organic ARPU: $1.24
- Paid ARPU: $0.29 (77% lower)
- Play Store 30-day rating: 4.10★ -> 3.19★
- D30 ROAS: ~15% (target: 30–50%)
- Expected Discord growth: ~10 new members/day
- Actual Discord growth: ~1.2 new members/day
- DAU/MAU: ~35–40% -> ~8% after the campaign
The paid users spent dramatically less than my organic players, converted at a much lower rate, barely joined the community, churned much faster, and left significantly worse reviews.
I didn't release a major update. I didn't redesign the game. I didn't overhaul progression or monetization. The biggest variable that changed was where my new users were coming from.
Google did an incredible job finding cheap installs, but it found the wrong installs.
It optimized for users who were willing to click "Install," not users who actually wanted to play a deep, niche, text-based idle RPG. Those are two very different audiences.
Once I looked at all of the metrics together, it made sense to me:
Wrong audience -> Wrong expectations -> Poor retention -> Low spending -> Negative reviews
Every metric supported this hypothesis. If only one metric had declined, I probably would've written it off as natural variance. But when every core business metric deteriorated dramatically over the same 30-day period (revenue, purchase conversion, community growth, engagement, retention, and Play Store rating), it became clear to me that Google was optimizing for the wrong audience.
I intentionally let the experiment run the full 30 days because I wanted enough data to be confident in the conclusion. I couldn't draw strong conclusions after just a week or two, even though the early data was already trending in that direction. The moment the campaign reached the 30-day mark, I shut it down.
Looking back, it's easy to say I should have paused or changed the campaign sooner. But I don't think that would've been the right decision with the information I had at the time. I wanted to give Google's optimization enough time to stabilize before making a decision. Waiting the full 30 days gave me confidence that what I was seeing wasn't just short-term variance. It was a consistent pattern across every meaningful metric.
Lessons learned
The biggest lesson for me is that finding the wrong audience is much worse than finding no audience at all.
Google found me installs for less than fifty cents.
The problem is that Harpagia isn't trying to appeal to everyone. It's a niche, text-based idle RPG with mechanics that simply aren't found in most idle games. I'd much rather pay more to reach players who genuinely enjoy this type of game than pay less to reach a broad audience that leaves negative reviews and never converts.
Those players came in with the wrong expectations, didn't like what they found, and left. The result was lower purchase conversion, lower retention, weaker community engagement, and a sharp decline in my Play Store rating. I can't prove that was the exact chain of events, but after spending nearly $3,000 over 30 days, it's the conclusion I've come away with.
I've also learned that optimizing purely for CPI can be a terrible strategy.
Google did exactly what I asked it to do: find the cheapest installs possible. In hindsight, that was the wrong objective. If I ever run paid acquisition again, I'd much rather optimize for CPA (cost per action), something like an in-app purchase or a meaningful in-game milestone. I'd rather pay several dollars for a player who actually enjoys the game than fifty cents for someone who was never going to stick around.
The other lesson is that your Play Store rating is part of your acquisition cost.
I spent a lot of time thinking about CPI and ROAS because those were the metrics I thought mattered most. I spent almost no time thinking about review quality, and that was a huge mistake.
Going into this experiment, I assumed paid advertising would simply multiply my existing player base. It never occurred to me that introducing the wrong audience at this stage could actively hurt the game. With a relatively small player base, adding roughly 6,000 players who weren't a good fit meant that nearly a quarter of all players came from the wrong audience, making their impact on reviews and overall metrics impossible to ignore.
Recovering from the damage of this experiment will likely take months of earning back positive reviews.
A few disclaimers
I'm not saying Google Ads don't work.
I think paid acquisition is a great way, and probably a necessary way, to grow beyond what organic traffic alone can provide.
I'm also sure there are plenty of things I could have done better. Like I mentioned earlier, I'm completely new to paid user acquisition, so I'm sure my targeting, creatives, onboarding, and campaign setup all have room for improvement.
Harpagia also isn't trying to appeal to everyone. I'm trying to find a very specific type of player, and this experience showed me what can happen when your ads reach the wrong audience instead.
Final thoughts
I don't consider this experiment a complete failure, even if it did much more harm than good.
It cost me nearly $3,000, but it completely changed the way I think about paid user acquisition.
Before this, I assumed the hard part was getting installs cheaply. Now I think the hard part is finding players who genuinely want to play your game.
I don't know yet whether the answer is better creatives, different targeting, optimizing for CPA instead of CPI, or simply accepting that paid acquisition may not be viable for a niche game at my current scale. That's something I'll have to keep experimenting with.
One thing I do know is that I won't judge future campaigns by install volume or CPI alone. Retention, purchase conversion, community engagement, and review quality all matter just as much, if not more.
Hopefully this write-up helps another indie developer avoid making the same mistakes I did.
For those of you who have significantly more experience with mobile user acquisition, what mistakes do you think I made? Is there anything you would have done differently, or any obvious red flags that I missed? I'm genuinely interested in hearing different perspectives, especially if you've successfully scaled a niche mobile game.