Maybe you're confusing it with top-level statements? This new feature doesn't even require a csproj.

No, I do absolutely remember them integrating dotnet-script-like functionality into the runtime, and I remember experimenting with it.

Was it only in a beta version and removed to re-appear now? It used the Rosyln compiler to compile on demand and then execute it, and used pragma directives that were compatible with dotnet-script's. I cannot remember what the shebang was set to, but it wasn't the same one as dotnet-script.