Hello Curious Minds! Create OBS overlay using Unity is way more simple then most of people think.
OBS have a Game Capture Input that supports Transparency, and this is half of the hard work done!!
To make a Build compatible whit this feature, is a little trick, because you think.. well let's render de camera as depth only, but this not work as it should be, at least on Unity 2018.4.19f
Maybe some blit the buffer need to happen, I really didn't dig on this to much, I just made a build with solid green and it's simple worked with transparency.
Make sure your alpha is ZERO on the solid color. This Clean the background every frame and also keep the transparency.
What's happens on Depth Only is they replace only the pixels with depth value. so you going to end up with a frame ghost as the don't clear...
Build, and Run you app.
On my case the Fancy name is because I use this project to make some shaders and some experimentation..
On OBS create a new Game Capture
Just choose if your app are running in windowed or full screen, and with Window/app the capture will hook
Make sure you check Allow Transparency
That's it! It's Working!!
I hope this help you do something cool ;) Cheers!