When someone plays a game, the user's goal could be expected as "having fun for as much time as they want to." Being addictive is usually in service of that. A "slightly dark" pattern would be combining core addictive gameplay junctures with microtransactions (retry/next level/upgrade) — but in this economy this just feels like a basic mobile game business model. A moderately darker pattern would be making the game increasingly frustrating while still addictive, unless you perform a microtxn (eg: increasing difficulty exponentially, and charging money for more lives/retries or forcing more ads).
A "true dark pattern" would be sneaking things like push notification permissions, tracking permissions, recurring subscription agreements, etc. under an interface that looks similar to something the user doesn't read carefully and tries to get past out of habit, such as an interstitial ad with a "skip" button — but with a below-the-fold toggle button defaulted to "agree" and a "Confirm" button styled to look like the "skip" button at first glance.