The key insight on top of raoGUTSGrandUnified2018 is that the different modes are hierarchical.
My expansion on this is that the modes are actually fractal — when you’re in Play mode there are sub-quests, explorations, or projects. Every time you zoom in on a fractal, it presents the same pattern on a different scale. A quest has sub-play, exploration, or projects. Etc. Even projects have sub-quests, explorations, and play. Even if the path forward seems straightforward, you might need to figure out a creative solution based on a new context, etc. (This is why even if a prototype works, manufacturing the thing is hard Manufacturing is important and often ignored)