It's not quite a SHMUP, it's more of a dodge 'em up mixed with a bit of brain game but I feel it has that high action spirit that is found in SHMUPs... Anyway give it a whirl it's free!
here's a vid of an ok run i did: https://www.youtube.com/watch?v=NoJCSuoQIlY
and here's the app store link: https://itunes.apple.com/us/app/i-heart ... d890649785
Enjoy!