I am a huge fan of open world games. I love exploration, and I can't stand invisible barriers that stop you from going certain places.

I also love generative design, I think it makes for really interesting gameplay, and increases the enjoyment of replaying.

Both my games (see my signature) are generative. Star Explorers is an open world space exploration game.

As for being practical, that is an issue. I have been working on Star Explorers since 2013, and it's still very rough around the edges (as well as having some major problems that I hope I just fixed). I plan to keep working on it for about one year before I give it a full release, but I've already decided that my next game will be much more limited in scope.

So ideally - open world and generative, but practically, for a small studio, or individual like me, it's probably better to limit the scope, or be prepared to spend a long time.