The developers of different kinds of games will have different motivations. A developer of traditional games might think, "How can I make this game better in a

The developers of different kinds of games will have different motivations. A developer of traditional games might think, "How can I make this game better in an aesthetic, or an educational sense?" Or, "How can I make this game a better FPS than the ones before?" A developer of another game might think, "I want to make money, let me survey existing games and read psych literature and create the next billion dollar game. I don't care what form the game takes, or what players get out of it." The claim is not that game developers for each game are creating an addictive game from scratch by A-B testing, but rather exactly what you said, that they're AB testing for smaller improvements in eyeball-retention, spending, and addictiveness, because all they care about are those metrics which drive profits (or valuation which can be converted into profits). That a set of conscious design choices, on its own, isn't sufficient for extreme addictiveness doesn't change the fact that those conscious design choices are necessary, and those choices are being examined, analyzed, and documented by other game devs and by psychologists. So, of course you can take all the known lessons and apply them to a brand new game concept and fail horribly, but if your game is a success on other grounds and you mined other games and the literature for addictive ideas, you are much more likely to have a billion dollar super-addictive game than you would have been 20 or 30 years ago.