Xydonia is a horizontal arcade shoot 'em up inspired by the Japanese classics of the '90s. http://breakingbytes.tumblr.com/ https://www.facebook.com/xydonia/ (GIFs are faster than actual gameplay) I'm 100% not involved with development or PRs, but I really like a game like this on iOS... And you?
Any of the Japanese arcade classics would be great for iOS. I hadn't seen Xydonia but it looks a good one; maybe It will be ported to iOS in due course. In the meantime Tengai is available and is a good rendition of the original 1996 side-scroller. There are probably others. Just a matter of finding them.