There's no such thing
I once watched my (teenage) niece playing Magic Tiles 3 on her tablet. It’s a free musical game that’s pretty fun, but it has lots of marketing videos interrupting gameplay all the time. Since one of my kids wanted to play it, I ask her if there’s a purchasable version, or another similar game that I can buy and that wouldn’t have the annoying ads.
She looks at me, slightly confused. “I don’t know about any game that doesn’t have ads. There’s no such thing, I think”.
So yeah, that’s what you’re up against, game developers.