Tools for systems design:
**Machinations** - design, balance and handoff game systems:
https://machinations.io/
this is an incredible tool that finally makes game system design legible.
**Loopy** is a tool for thinking in systems, made by Nicky Case
https://ncase.me/loopy/
this one is more general-purpose, but simplified.
[[The Garden of Eden Creation Kit (GECK)]]