Write Unity C#. Run it in VRChat.
Udonite compiles ordinary Unity C# to Udon. There is no dialect to learn and no list of forbidden keywords - the code you already write runs in the world as it is. The hosted services cover the parts a world cannot do on its own.
Get the compiler
Free, and it stays free. Paste this listing into the VRChat Creator Companion, then add Udonite from the package list.
https://udonite.github.io/vpm/index.json
Add to VCCThe compiler
C# in, Udon out. Generics, interfaces and the rest are compiled rather than reimplemented, so you write what you would write in any Unity project.
Hosted services
Send a message from a world into Discord or Pushover, and keep a counter, a score table or a shared switch that survives everyone leaving.
Free to use
The compiler is free, and stays that way. The hosted services have a free tier big enough to build against; supporting raises the limits.