(CNN) -- Your app store may be getting a lot less flappy.
Both Apple and Google appear to be cracking down on new apps taking advantage of the demise of "Flappy Bird," the addictively simple casual game that became an unlikely sensation before its creator abruptly pulled it off the market last week.
Even before "Flappy Bird" topped the download charts last month, a cavalcade of knock-off games began appearing. A quick search for the word "flappy" in the Google Play store on Monday returned 250 results, from "Flappy Pig" and "Flappy Fish" to "Flappy Troll," "Flappy Cat" (yes, it's the Web's beloved Nyan Cat) and even "Flappy Bieber."
Then came Vietnamese developer Dong Nguyen's abrupt announcement he was going to pull "Flappy Bird" from online stores. The resulting wave of publicity created even more demand for the game and others like it.
But now, developers say both major mobile players are pushing back.
"This is just not my f---ing week: Rejected. 'We found your app name attempts to leverage a popular app'," Ken Carpenter of Mind Juice Media tweeted Friday. "Which app? FB doesn't exist!?!?!
Carpenter said he had submitted a game called "Flappy Dragon." Several developers responded to his post, saying they had gotten similar notices from Apple and Google.
Neither Apple nor Google immediately responded Monday to a request for comment.
An Apple spokesperson told tech blog The Verge that the company is cracking down not just on apps with the word "flappy" in the title, but all apps that appear to be trying to trick customers into thinking they are associated with or replacing a popular original.
One developer told App Battleground that he retitled his popular game "Flappy Bee" as "Jumpy Bee" several days ago after getting an e-mail from Apple saying he had 48 hours to change the name.
After existing in relative obscurity for months, "Flappy Bird" took off in popularity late last year and became the most popular free app in both Apple's App Store and Google Play, the store for Android apps.
At its height, the game was earning Nguyen an estimated $50,000 a day through advertising, an obvious reason others hoped to piggyback on its success.
Nguyen said he was pulling the game, which took him two or three days to create, because it had become an "addictive product." After he pulled it, smartphones with the game already installed began popping up on eBay, with some sellers asking tens of thousands of dollars.
While the app is no longer available, Nguyen is still earning money off ads viewed by the millions of people who had already downloaded it.