Like the term RPG, Open world and even sandbox have been appropriated for PC games and have taken on different meanings.

Open World tends to mean a game where you can roam wherever. There are no barriers really so if you go over there you might get your head handed to you, but over here its manageable. Id guess its use is closer to a wilderness or hex crawl campaign for tabletop.

Sandbox in PCs seems to still have no real definithion. One guy uses it for an open world game, another uses it for a fixed but destructable map, another uses it to describe any given builder game like Minecraft. And someone else uses it to describe some sort of rail shooter, but you can custom your gear. Oh and its an RPG too. No really! It is!

It does look like the OPs game is of the open world sort. Free roaming. That is the impression I got from the vid.

Looks like actually asking questions killed this thread, and possibly the OP.

Hopefully to think on how to improve things and assess the feasibility factor.

Playtesting is where the real fun begins.