12 years old is definitely old enough to play Monster Hunter. Most kids in Japan probably start playing it at around 7 or 8. Coop is a lot of fun, unlike what someone else said you don't need friends to play it online. Having trouble ? You can, whenever you want, call for help, and other players can join you on the hunt. You don't need to grasp all the subtilities of the system. I've finished the DLC, Iceborne, almost entirely by playing coop and I just know the basics of Monster Hunter. You hit monsters, kill them, make armors and weapons out of their bones. Repeat. I know how to craft electric traps in order to capture them, I know how to craft a few potions, and there you go, I don't use any other items lmao.
Star Wars was, to me, really boring. Also, it's a metroid-like game, so progression is not linear, make sur your child enjoy that kind of thing. It's not a linear action game, it really is a metroid like game that is a little bit more focused on combats.
Anyway, my vote goes, without a doubt, to Monster Hunter World. Though you have to make sure they will like that kind of stuff. It's a bit repetitive. It's just boss fights, again and again. And you'll kill the same monster dozens and dozens of times.
