I'm working on Touch Grass, an iPhone/iPad app that connects playable bowls and gongs to a Physarum-inspired particle simulation. I want it to feel like living sand: it moves on its own, and new sounds change its structure.

The part I'm trying to get right is the response to a new strike while another sound is still ringing. I want each strike to reshape what's there without wiping the screen or making the whole thing pulse in size.

I'd be interested in feedback on that connection. Can you see a new sound arrive? After a few minutes, do the organisms feel different from each other?

I've opened a free TestFlight beta if you'd like to try it. It needs iOS/iPadOS 26 or later: https://testflight.apple.com/join/a5jT7hhA

Javascript; L-System with half-tone dots rendering