[michaelone]

Interesting, do you have data on Flappy Bird itself? Apple might normalize their data for those kinds of anomalies like Modern War's blip, but your Magic Piano example does show a rise in ranking both of the times they had an upswing in reviews.

Apple does seem to weight installs over time, so I wouldn't be surprised if they also weight reviews over time to catch those kinds of push notification strategies. Zach Williams's data showed something quite different than Modern War's: more of a snowballing after the initial climb, so maybe the consistent influx of reviews from the in-game button was a "normal" enough data point to get past Apple. Nobody obviously knows for sure all of the details of Apple's current algorithm.