It is a marketplace from Side Effects that offers a nice way to create animations and visual effects. Orbolt assets are fully customizable, and you can animate and render them the way you like.
The platform features a set of completely customizable 3D assets: fully-rigged props, render-ready visual effects, animatable characters, game assets, and more.
The best thing is that can use these assets in other applications with the Houdini Engine plugin such as Maya, Unity 3D, Unreal Editor, Cinema 4D, and more.
You can learn more by visiting the official page. Also, make sure to read our extensive overview of Houdini 18 here.