My wife is a sucker for these horribly generic flashy F2P puzzle-ish games. There are these ads that pop up every N action or something; some of these look like a mini-game and are actually an ad for another of those F2P games, and you have to play the mini-game that showcases some dumb simple mechanic of the game it advertises for a little bit before you can dismiss the ad.
Some come complete with two trivially easy levels ONLY 20% OF PLAYERS CAN PASS SOLVE THIS that glorify you OMG YOU HAVE SUCH HIGH IQ then one impossible that taunts you into installing the game.
The predatory dark patterns are so obvious they should be trialed to oblivion but no apparently this kind of abuse is legal.