I believe "sandbox" vs. "railroad" is a spectrum, not a binary choice, and largely a false dichotomy. I mean, seriously, who actually runs a pure railroad game, except maybe to introduce first time players? One does not run a sandbox game; you run a 'more sandboxy' game. All the characteristics the OP imparts to this sort of game can and should also be applied to a more railroady game, too, and therefore should be titled "8 words to help run a roleplaying game".
Furthermore, what is the true value of sandbox? So that the players believe their choices matter? In that case the illusion of a sandbox is as good as a real sandbox. E.g., no matter which road the players take, they encounter the same important traveling tinker NPC. As long as the players never catch on, this works perfectly fine.