GamePigeon

I am trying to play Gamepigeon with some friends, but when I try to click on the game it sends me to the app store. It says I have it downloaded and all I have to do is open it, but it won't open. I thought well I will just try to uninstall and reinstall but I don't know how to do that when It doesn't show up in my apps bar. I am unsure of what to do.