For those unfamiliar with the term, a "Billboard" sprite is a 2D image that always faces the camera, so the player can't "see around it" to notice that it's just a flat image. You've undoubtedly seen this done in old games like Doom and Wolfenstein 3D (even the corpses of the monsters would continue to rotate with the camera).

I've always wanted to experiment with this old school technique, and Ludum Dare seemed like a great time to try it out, especially because I don't have any 3D modeling experience but wanted to do a 3D project.

I thought it would be fun to share what it looks like in Scene view compared to the Game view in Unity. Pretty funny to see what the sprites are actually doing in response to the camera motion. The script attached to the sprites is super simple:

void Start()
{
    cam = Camera.main;
}

void Update()
{
    transform.forward = -cam.transform.forward;
}

If you want to see this in action and nuke some Ghost Spiders, please play and rate "Darkling" here:

https://ldjam.com/events/ludum-dare/44/darkling