Looks like an interesting app for making music rapidly. I’m going to give Polychord a try very soon and I’ll let you know what I think. Here’s the app’s description though:
Whether you’re an absolute beginner or an experienced musician, you’ll love polychord. Write songs or play along to your favorite tunes. You can use up to 10 fingers at once on the polychord to create chord progressions, melodies and harmonies, and there are lots of beats to choose from. When you’re feeling retro, turn on bitshift to give polychord that 8bit sound.