If you have any Radiant tutorials please share.

http://icculus.org/gtkradiant/

Some tutorials by cityy

https://youtu.be/1MWbP3nKEIA Part 1: getting started

https://youtu.be/Fte5pzmKjkE Part 2: Navigating in GTKradiant

https://youtu.be/8GCfeiUw9JU Part 3: Making your first room

https://youtu.be/TwyleBOH7W8 Part 4: Connecting two rooms, Jumppads, Teleporters

https://youtu.be/sjMHgamtuK0 Part 5: Creating a simple door

https://youtu.be/b-GvXTUkXP4 Part 6: Liquids (Water, Lava)

https://youtu.be/gsXYCvjPl3E Part 7: Two-Point Clipping (Angled Corners)

https://youtu.be/dQt4s36UmrU Part 8: Grid Size, Edge- and Vertex Editing

https://youtu.be/BW33w0-z0Qk Part 9: Curved Surfaces