This addon changes the chapter icons for the old and new UI.
HL Source Style Icons on the Black Mesa Workshop can be found here:
This addon is mostly for me, but I posted it because maybe you will like it.
If you don't like these icons because there may be spoilers in the image, you don't have to.
I also made a second version, but the icons are basically from the background maps.
So you can think of it as High-Quality Chapter Icons.
Here are my other edited Chapter Icons (but not all are original):