Pretty neat and very difficult. Maybe have a slower introduction, but it's not necessary if you want it to only be a hard game (since it's so short). I disagree with armo on the PC version not needing to hold down. Pausing by letting go was a fine feature even for PC. If you want to please both, you could have a toggle option somewhere.
You know about these two issues, but chronicled here in case you want a permanent log: Error on loading with Firefox; lag first time you drag on Chrome.
Great short game. Go publish it on the android store or something!