There was once something akin to Droplets on early iPads but I can find no trace of it now.
You add taps across the top and bars (tuned by their length) beneath. The flow of drips from the taps can be adjusted by rotating the tap.
With an array of options from setting a scale to tweaking the built in synth or sending midi out to other instruments it is both useful and fun.
For endless tweaking Stacks may satisfy. Following on from Strokes it is a sequencer/looper/granulator thingy. Currently in an early release version with several features ‘coming soon’.
More noise you say then obviously SoundDust’s Hobbes is what you are looking for.
With which you can Ooof and Doof to your heart’s content – or just click all the dmoRan options…
But for some serious randomness the Eclore player provides pieces that play in Reaktor and can be remixed to provide countless variations.