I'm going to disagree here. It reminds me of the "Python Ninja"-type job titles that became popular ~2012. It's so preoccupied with standing out and breaking the formality of its medium that it actually says nothing.

The repo description literally says two things: Circle is a C++ automation language, and Circle trained with the League of Shadows. The rest requires clicks.

That's a terrible way to drive adoption for something that obviously was difficult to build. Sometimes being earnest and straightforward is the best way to break down skepticism, not by using meaningless hipster taglines.

there's about a zillion pages of detailed documentation on top of that

The intro text is not detailed enough to tell me whether I want to click on any of those.

How hard is it to write a one-sentence explanation of what a project is that doesn't involve ninjas?

From the abstract,

"Circle is a compiler that extends C++17 for new introspection, reflection and compile-time execution. An integrated interpreter allows the developer to execute any function during source translation. Compile-time flavors of control flow statements assist in generating software programmatically. The configuration-oriented programming paradigm captures some of the conveniences of dynamic languages in a statically-typed environment, helping separate a programmer's high-level goals from the low-level code and allowing teams to more effectively reason about their software."

While I appreciate your qualm, respectfully I think that no matter how it were introduced, someone would've quibbled. "You should be straightforward", "you should be more detailed", "you should have more ninjas". There's no win. The solution is to hope the readers you care about will be adventurous enough to make two clicks.