Which knobs a game can still change after export

A parameter is only reachable from game code if its node is exposed. Use the toggle in the node's header. Without it the value is baked into the exported file as a fixed number, and nothing in your game can reach it.

Exposing a node is necessary but not sufficient. Some nodes build their geometry when the file is exported and cannot rebuild it at runtime, so their knobs appear in the panel and still export as fixed values. A few settings go further, because the target has nothing to carry them with at all: a Roblox part has no index of refraction, so that value never reaches the exported file, not even as a fixed number. Before you export, the dialog checks the graph and shows the warnings and errors the export would produce, including any branch it has to freeze to a fixed snapshot.