I just played it a while on my 6+ (iOS 9) and it did not crash. I can see how a crash at the end of a good run could be aggravating! But in my (limited) testing it's not a constant issue. (Maybe, if there is a crash and it can't be fixed, progress-saving between sessions could handle it?)
Great news! Michael Brough just remade Zaga-33 with the Godot engine and rereleased the game on the App Store! It‘s also available for Mac, Windows and even Android via his itch.io page. So happy to be able to play one of my fav games again.