We’re big fans of US apps developer Smule, whose Magic Piano, I Am T-Pain, Glee Karaoke and MadPad apps have been great musical fun. Now the company is getting into iPhone gaming with new release Beatstream. It’s an action-rhythm game that sees players taking control of a “two-faced arrow”, smashing through barriers in time to music. Here’s the thing though: whereas Smule has used previous apps to sell music as in-app purchases, that model appears to have been ditched for Beatstream. Instead, it uses songs from players’ existing iTunes libraries on their phones as the basis for tracks. “Turn your iTunes library into a game and customize your experience…” As such, it struggles with DRM-protected songs bought from iTunes before 2009, and also has issues with songs stored in people’s iTunes Cloud accounts that haven’t been downloaded to their device.