I just looked into developer console and noticed that latest update of Magic Hearts crashes.. a lot :( I didn't see the crash reports before (it has been more than two weeks from the update..), because console didn't show them to me (eh..). It may explain so many uninstalls lately..
I have released an update (version 1.30) with the crash fix (I hope). I am sorry for releasing crashing update. I try not to do that (believe me or not :)).
FYI: It may take a while before Magic Hearts will be available on Google Play.