Ever since Flappy Bird gained popularity because of its awfulness, there have been a number of clones littering the App Store. One of them is ‘Ironpants’.
Ironpants is almost the same as Flappy Bird with just two minor changes. The first difference in Ironpants is that you need to keep the finger pressed against the screen to get the superhero fly higher, unlike Flappy Bird in which tapping the screen takes the bird higher. Secondly, the superhero in Ironpants moves faster than the bird in Flappy Bird, making it difficult to control.
To be perfectly clear: If Flappy Bird were still on the App Store, I’d probably not recommend checking out Ironpants because it is indeed the inferior product. However, with Flappy Bird’s creator promising to never re-publish the game after he removed it from the App Store, it’s the only halfway decent alternative currently available.