After hardening the whole system and capseling it into its own project, I can move on with other needed functionalites for it. Ah yes, also I versioned it with git, since my ultimate goal is it, to publish InterAction System on GitHub.
I needed for my adventure game the Quest Nodes and obstacles. The Quest Nodes (you could also call them location triggers) were allready in places, but not using the Flag System.
A QuestNode is a box collider set to a trigger, that, for now plays a sound and shows a message, optionally depending on flag settings.
A FlagDependent Obstacle is basicly the same, but instead of triggern it blocks passage depending on flags.