Sandspiel by Max Bittker and contributors. MIT (LICENSE.txt). Fluid simulation by Pavel Dobryakov, MIT (notice retained in source js/fluid.js). Runtime libraries: THIRD-PARTY-NOTICES.txt.
Upstream https://github.com/MaxBittker/sandspiel revision 9936e06b07a583aedfba9589c0cead2917f405fb.
Leaf Arcade changes 15 October 2026: local-only palette and responsive controls; keyboard painting, pause and local scene persistence; ads, analytics, gallery/accounts, service workers and unrelated assets omitted. Rust simulation, original painting rules and WebGL shaders retained. Source and build instructions: source/. No affiliation or endorsement is implied.