I love to write F# (I built FVim), but there's still gap towards high performance game programming. In C# you get a lot of low-level unsafe constructs with zero allocation overhead that integrates very well with the external libraries. In F#, you either get a clumsy library special form (without proper syntax support), or the idea itself is considered "only for C# interop uses" and thus not prioritized.

F# has been in this position: a smaller team that tries to align with C#, without a language implementation team backing them (unlike Roslyn-C#), yet constantly feeding innovations back into the dotnet ecosystem. You can see a lot of example where F# piloted the idea, and later C# adopted and extended it in its own way, and F# struggling to catch up in that OO-centric world

(Disclaimer: MS employee, but not on the language teams)

Why F#?

I need a good reason to use one more programming language and one more dependency.

Also, how many Unity examples and tutorials and knowledgeable people are using C# and how many F#?