The game became a service. The "sell a copy and walk away" model gave way to "retain and monetize over months": the master metric is retention, the money is carried by variable rewards (gacha) and seasonal FOMO (the battle pass), decisions are made by telemetry and A/B tests, and toward the end of the era privacy (GDPR + ATT) knocked out the data all of it stood on. This is the era where design met behavioral psychology and experimental statistics — with all the ethical seams that implies.