When Flappy Bird left the Play Store and Apple's App Store, it left a vacuum. And since it was pulled, that vacuum has been pulling in all kinds of lint, in the form of knockoffs, clones, or games that simply want to use Flappy Bird's success as promotion for their own games.
It would seem, though, that Google (along with Apple) has begun taking steps to prevent the store from becoming overrun with such entries. As Tech Crunch reports, multiple developers have complained that Google Play, the Appstore, or both have rejected their recent Flappy efforts, multiple times in some instances.
According to developer Ken Carpenter (cited above), Google did not provide any warning before yanking his game Flappy Dragon. As Tech Crunch reports, Google cited the Play Store's "spam" policy as the reason for taking down the listing. Carpenter explains:
The message they sent me simply referenced the ‘spam’ provision of the Google Play terms and did not specifically call out what my transgression was.
Source: Tech Crunch