Love this! I tried this on my phone and instinctively tried to turn my phone to make the pieces slide around (after seeing the falling/sliding physics), expecting them to react to the gyro in the phone. Then realized, right, this is a web app!
Thanks for the feedback, using the phone's accelerometer is actually a great idea!
As others mentioned, there are web APIs for that these days, I'll try to include something like that in the next version.
Great work, fun!