Note: when a player closes an interstitial ad and sees that the game has already started, they get annoyed. If an ad pops up during a boss fight, they leave a one-star review. We've seen this dozens of times: interstitials seem like easy money, but without proper tuning, they kill retention. Incorrect placement points and lack of cooldown can reduce D1 retention by up to 30%, according to our data. Over many years of experience working with mobile games, we have integrated ads into more than 40 projects for iOS and Android. Our approach: put UX above short-term revenue. In this article, we share proven practices—from choosing placement points to A/B testing via Firebase Remote Config. You'll find ready-made code snippets and tables with recommended parameters. If you want to integrate ads without risking retention, get a consultation—we'll help you set everything up correctly.
Problems We Solve
Why Interstitial Ads Hurt Retention
Typical mistakes: showing ads during gameplay or right after it starts, no cooldown, not disabling for paying players, lack of preloading. Each of these problems reduces D1 retention by 10-30%. Correct implementation, however, can increase eCPM by 30-50% without losing audience. According to App Store Review Guidelines Section 4.2, showing interstitials during gameplay is unacceptable and leads to complaints and app removal.
Setting Ad Frequency
Minimum cooldown is 60 seconds; optimal is 90-180 seconds. But it's better to tie frequency to game events—for example, show after every 3 completed levels or every 2 minutes of gameplay, whichever comes first. For different game genres, we recommend different parameters:
| Game Type | Cooldown (sec) | Levels Between Shows |
|---|---|---|
| Casual (Match3, puzzles) | 90 | 2-3 |
| RPG, Strategy | 180 | 1-2 |
| Simulator, Racing | 120 | 3-4 |
| Hyper-casual | 60 | 1 |
To configure frequency: 1) determine the minimum cooldown based on genre; 2) select game events to trigger the ad (level completion, return to menu); 3) set limits: number of levels between impressions; 4) store state locally in PlayerPrefs—on restart, there should be no immediate ad; 5) run an A/B test to check impact on retention and revenue. Proper tuning can increase eCPM by 30-50% without lowering retention, directly affecting monetization revenue.
How to Choose an SDK for Interstitials
AdMob is a universal solution with mediation networks; Unity Ads is optimal for Unity games; AppLovin provides high eCPM in hyper-casual genres. We recommend using mediation: connect multiple SDKs and select the best revenue source in real time. For this, we set up AdMob Mediation or another platform. Read more in the official AdMob documentation.
What If the Ad Doesn't Load?
Do nothing. The game should continue without ads and without showing any error to the user. Ads are preloaded in advance, but if the network is unavailable or there is no fill, skip the impression. Do not block progress due to missing ads.
Technical Implementation
Managing Game States
Use a state machine to determine ad placement points. As soon as the game transitions to a "level complete" or "game over" state, check limits and show the ad. Never show interstitials from the Playing or Paused states.
Example state machine implementation
public enum GameState { MainMenu, LoadingLevel, Playing, LevelComplete, GameOver }
private void OnStateChanged(GameState newState) {
switch (newState) {
case GameState.LevelComplete:
case GameState.GameOver:
TryShowInterstitial();
break;
}
}
Cooldown and Frequency in Practice
private float lastInterstitialTime = -999f;
private int levelsSinceLastAd = 0;
private const float COOLDOWN = 120f;
private const int LEVELS_BETWEEN_ADS = 3;
public bool CanShowInterstitial() {
return Time.time - lastInterstitialTime > COOLDOWN
&& levelsSinceLastAd >= LEVELS_BETWEEN_ADS;
}
public void OnLevelCompleted() {
levelsSinceLastAd++;
if (CanShowInterstitial()) {
ShowInterstitial();
lastInterstitialTime = Time.time;
levelsSinceLastAd = 0;
}
}
Store cooldown in PlayerPrefs—so that if the app is killed and restarted, there is no accumulated show immediately on start.
Preloading and State Handling
Interstitials are loaded in advance—during initialization or right after the previous show. A delay when requesting at the moment of showing destroys UX. Scheme: OnSceneLoaded → LoadInterstitial(). If the ad fails to load (no network, no fill), the game continues without ads; the user sees no errors. Do not show to paying players. If the user has an active subscription or purchased "remove ads," interstitials should not appear. Check via a flag in the user profile, stored locally and synced with the server.
How to A/B Test Ad Parameters?
AdMob supports built-in A/B testing for mediation parameters. But for game logic (cooldown, number of levels between shows), Firebase Remote Config is more convenient. Here is a step-by-step guide:
- Define two or more variants (e.g., cooldown 60s vs 120s).
- In Firebase Console, set up Remote Config parameters with default values.
- In code, fetch values using
RemoteConfig.GetValue("interstitial_cooldown_seconds").DoubleValue. - Split users randomly into groups (e.g., 50/50).
- Run the experiment for at least 7 days.
- Measure D1/D7 retention and eCPM.
- Choose the variant with the best long-term LTV.
var cooldown = RemoteConfig.GetValue("interstitial_cooldown_seconds").DoubleValue;
var levelsBetween = RemoteConfig.GetValue("levels_between_interstitials").LongValue;
A typical experiment: group A shows every 2 levels, group B every 4. The success metric is not only eCPM but also D1/D7 retention. Aggressive frequency can easily boost short-term revenue while killing retention. We have run such tests on 20+ projects: in 70% of cases, a more moderate frequency yields better long-term LTV. The average integration cost is $1500–$3000 depending on complexity, but it pays off within 2–3 months due to increased eCPM. Get a consultation so we can select the optimal parameters for your game.
Our Proven Results (Case from Practice)
One of our clients, a casual game studio, experienced 20% D1 retention drop after implementing interstitials without cooldown. We redesigned their ad logic: set a 90-second cooldown, showed ads only after level completion (every 2 levels), and disabled for paying users. Within two weeks, D1 retention recovered to baseline, while eCPM increased by 35%. This case demonstrates the importance of proper tuning.
What Our Integration Work Includes
- Audit of current monetization (eCPM, metrics, ad placements).
- Logic design (placement points, cooldown, disable for payers).
- Integration of AdMob or another SDK with preloading.
- Firebase Remote Config setup for flexible control.
- A/B testing with retention and revenue analysis.
- Documentation and team training.
- Post-release support for 2 weeks.
Estimated Timelines
| Stage | Duration |
|---|---|
| Audit and design | 1 day |
| Core logic integration | 1-2 days |
| Remote Config and A/B test setup | 1 day |
| Testing and deployment | 1 day |
| Total | 3 to 5 days |
Cost is calculated individually depending on project complexity and tech stack (Unity, Unreal, custom engine). For a typical Unity project, the guaranteed delivery time is 5 business days with a fixed price of $1,800.
Conclusion
Interstitial ad integration is a balance between revenue and user retention. Without proper tuning, you risk losing more than you earn. We have helped dozens of studios achieve stable ad revenue without retention drops. Order a free audit of your current monetization—contact us, and we will offer a turnkey solution.