Emacs, the text editor that lets you read mail and play Tetris, is often cast in opposition to the Unix philosophy of "do one thing well" and "combine small programs". It's a false dichotomy. Emacs can do a lot on its own and can be combined usefully with other programs.
run‑command makes the combination convenient through a simple configuration format and an interaction flow that stays out of your way. Instead of reaching for a shell or a specialized major mode, you give run‑command a simple "recipe" and you get a contextual command palette where you can browse, select, and run commands without leaving Emacs.
For demo, quickstart, and advanced configuration, see the documentation website.