We also try to reach out on here when we can 
I’m more on the FX/TA game dev side of things here. Regarding game FX, Houdini really only works on the DCC side of things. Since it’s designed more for accurate simulations, it would take too long for UE4 to utilize Houdini to compute things. So really, the best way to use it is to generate the textures you need and then integrate them into particle systems in-engine. For a list of things I’ve done so far:
-Fire
-Water
-Flowmaps
-Smoke
-Prefractured models
-Animated destruction
-Velocity Fields
-Flipbooks of various sims
-Meshes of various kinds to support FX
-Blood
-and more!
The best part about Houdini is that all I need to do is figure out a pipeline for a certain texture and then I can generate as many as I would ever want 
I never have to paint or video source textures.