An advertisement appearing after a mobile game round was not scheduled in advance. It was bought in an auction that ran while the round was ending, and the mechanics of that auction shape the game around it.
The slot is sold, not the ad
When a game reaches an ad break it sends a request describing the opportunity: the app, the format, the placement type and whatever is known about the device and audience.
Demand platforms bidding on behalf of advertisers evaluate that opportunity and return prices, and the highest acceptable bid wins the impression.
The whole exchange completes in a fraction of a second, which is why a slow network shows a loading spinner where an advertisement should be.
Bids reflect expected value, not the advertiser's interest in you
An advertiser bids what an impression is worth given the probability of an install or a purchase following it, which is estimated from historical performance on similar traffic.
American users typically command higher bids than most other markets because measured spending after install is higher, which is a market fact rather than a judgment about individuals.
This is why the same game shows different advertisement quality in different countries, and why revenue per player varies enormously across a global audience.
Format determines price more than placement
Rewarded video, where the player chooses to watch in exchange for something, earns substantially more per impression than a banner, because attention is voluntary and completion is high.
Interstitials that interrupt sit in between: more valuable than banners, more damaging to retention than rewarded formats.
Studios therefore design reward loops that give players a reason to opt in, since the format that pays best is also the one players dislike least.
Privacy changes altered the bidding inputs
Platform restrictions on cross-app tracking removed identifiers that bidders had used to estimate value, and prices for unidentified traffic fell accordingly.
Measurement moved toward aggregated and modeled attribution, which is less precise and gives advertisers less confidence in what an impression is worth.
Developers responded by leaning on contextual signals and on in-game behavior, which they can observe directly without cross-app tracking.
Mediation decides who gets to bid at all
A mediation layer sits between the game and multiple ad networks, deciding which sources are called and in what order for each request.
Older waterfall arrangements called networks in a fixed sequence at fixed prices, while bidding setups ask sources to compete simultaneously for each impression.
Moving from one to the other can change a game's revenue materially without altering a line of gameplay code, which is why monetization work often sits entirely outside the game itself.