Arma is an interesting example. I’d say that it is only an open world game in some scenarios, and often times is a linear game that happens to have a big map and sandbox.
In any case, I’d agree that it having a large world with many possibilities is important for the gameplay and ability to mod/create content across the maps.
Does the Mass Effect 3 multiplayer count, then? There are RPG elements, there are a bunch of playable women, and it is all about stomping hordes.
If this sounds appealing and you aren’t already aware: this is not available in the remaster. Andromeda has a version of this, too.