The best ad format for a mobile game depends heavily on genre: a hyper-casual game with two-minute sessions has a very different tolerance for interruption than a mid-core strategy game with 20-minute sessions.
By genre
Hyper-casual games lean hardest on interstitials and rewarded video, since sessions are short and monetization has to happen fast — often between almost every level or run. Mid-core and strategy games use rewarded video more selectively, tied to specific value exchanges like resource boosts, since their players are more invested and more sensitive to interruption.
Banner ads still show up across genres as a low-friction baseline, usually on menu or inventory screens rather than during active gameplay.
Matching format to session structure
The general rule: the shorter and more repetitive the session, the more a game can lean on interstitial frequency without hurting retention; the longer and more narrative the session, the more monetization should shift toward optional, rewarded formats.