I’m starting to worry about this while I was programming/practicing my Android project. The debacle is still going strong even after Flappy Bird was taken down by its author. There’s about 1/3 of the clones on the App Store for iOS.
Unfortunately, plagiarism is not possible with games. Games are not covered by copyright.
So, what do you plan to do about this? Combat it? Fight it in courts? Or just let them be?