I'm not kidding when I say it has the potential to become the blender for 2D/3D VFX -- the node engine is super powerful, the primitive building blocks are all well thought-out and integrate with each other very nicely, the performance characteristics are amazing (all optimized for realtime!), and there's a ton of I/O for everything from mouse input to OSC/MIDI, camera control, elaborate audio reaction... and also just plain TCP/UDP/HTTP/Websockets! It's such a powerful glue piece, but also tons of fun to mess around with on its own.
The best part? You can create your own components, define your inputs/outputs, and compose them together. The even bestest part? You can dig into the predefined components/effects and see how they work, as they're very often implemented in the same way! The visual editor all drills down to C# in the end, and you can drop into the code or write some HLSL shaders if you want, all with hot reloading.
Just give it a try, you won't regret it :)
Tixl: Open-source realtime motion graphics
https://github.com/tixl3d/tixl