One of the things we wanted to achieve in Grapple was to have a very non-intrusive HUD with minimal, if any, UI (we did have to make some exceptions). With that said, we needed a way to show players where lantern thieves were in the environment.
Within the game’s fiction, we had talked about the power lanterns giving off a kind of gaseous material or vapor of some sort. I took that idea and made a particle out of it. The idea was that the sparkly blue gas would rise into the air, high enough for the player to see, and the player could follow the trail down to find the lantern thief.
We ended up using another effect of mine for this purpose, and this particle was instead used for a particle trail in the ending cinematic.