(I know that this is basically in your upcoming features, but I'm going to re-iterate anyways for effect)
I like that it's an acorn falling from a tree, but the quality of the art is really low. Since you are making a flappy bird clone (and there are many already) you need to distinguish it from others, probably with quality of art. The thing I like about flappy bird was the silly splatting sound and animation of the bird falling when it knocked into something. If you could up the quality of all of the art, add a really nice animation for death, and an amusing sound on death, and a scrolling background, I could see it being good. Something that someone would play for more then 1 minute.