I find myself referencing Fallout and Skyrim a lot. They have fantastic editors. I've also mentioned this concept in the past of having a Blocking Zone. In Fallout and Skyrim they are called Collision Markers and are red in color. They simply prevents the player from passing.
I believe once you place an Blocking Zone/Collision Marker it has an infinite height preventing the player from passing it from below or over.
Its a must have to prevent players who seem to manage venturing into areas you don't want them to.
We are on the right track for Blocking Zones as the best ones are shaped much like the "sound zone" we currently have, with modifiable points.
(I've also been using invisible walls as a substitute)
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