I love the idea of the danger just being…plants. Invasive species? Although it’s really the humans that are invasive. Sure, there’s a BBEG to defeat, but the problem is much more n existential one of, “The climate is changing and we’ll lose our home and livelihoods” rather than, ‘evil monster over there’.
It strikes me that this could be quite useful when used proactively.
E.g. - Player Character Byrnwolf just got a crit on the Bandit Lord with his Greataxe. Queue the GM: “How comfortable would everybody be with a description of Byrnwolf splitting this guy in half?” All the players tap red, yellow, or green in response, and the GM can moderate from there.
It would be good at providing ongoing feedback for the GM to guide their style over time.