Whatever thing we're talking about, be it online media or TV shows or an activity or whatever, there's a thin line between "fun" and "addictive" - in order for anything to be "addictive" it must also be "fun", or otherwise nobody would get addicted to it. Even more - the more "fun" a thing is, the more "addictive" it gets.
In online media, engagement tricks have got a bad reputation (at least with HN-visiting crowd) because of the companies who pour huge budgets into "engagement research", A/B testing, dark patterns, and all the other stuff we hate.
However, discarding all fun things because they might be addictive would be throwing the baby out with the bathwater. So it is important to draw some kind of line between "fun" and "addictive".
Right now, the absence of user engagement data collection seems to be a good rule of thumb. So in conclusion, your widget is okay.
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I apologize if my question has offended. I did not mean to imply your personal work is "bad" in any way.