I like the idea, and sometimes it is fun to chill out and mess around with a little sequencer-type thing. But I felt this was really basic and lacked depth. Others have said to add some gameplay, but I'd say to add more complexity to the sequencing. Have an array of 64 loops to mess around with instead of just 16. Allow the player to build a couple of patterns and play them back in sequence. Stuff like that.
On a technical side, I found the audio started to clip when too many notes very being played at once. And that G# on the black cat is completely dissonant with the rest of the C Major scale.