People play games. So characters within a game should occasionally play games too. We've already seen Dejarik, of course, but there are plenty of other sorts of games. Such as children's games!
If you want inspiration for further use of traditional children's games within a serious roleplaying game, just take a look at Squid Game.
Commentary by memnarch (who has not seen the movie)
Haha, alright then. So maybe this wasn't a weird training thing. Maybe movie-Luke really just doesn't want to be bothered; he certainly looks like he's giving Rey the cold shoulder at the moment. The lighting is better so far in this movie, but it's looking like it's meant to be more cynical in exchange. I guess that'd make the downer opening work better if things are just meant to be that way with this Episode. I don't know if that'll make for a good movie in the end, but that would explain the design choices better.
I kind of wonder if Luke made all these huts himself or if they're just old remains he decided to move into. And there's probably a boat of some kind to go fishing from; this island is quite a bit more barren-looking for edible plants compared to a swamp. I'm sure the lichen plants or grass could make stew or soup of some kind, but imagine living on that for years! You'd have to tweak your taste-buds to put up with it.
Transcript
Rey: ... ninety-nine... one hundred!
Rey: All right, let’s think this through logically. No trees on this island. Precious few places to hide...
Rey: I check out the huts I passed earlier.
GM: You approach the huts, and hear a door creaking.
[SFX]: kree..ee..eek...
Rey: Ha, found you! You’re obviously inside the hut.
Luke: {inside hut} I don’t make any noise.
GM: You hear nothing from inside the hut.
Rey: I know you’re in there.
Luke: You don’t win hide and seek by knowing. You have to find the quarry.
Luke: This is out of character by the way. I’m still silent.
Rey: Fine. I open the door.
GM: It’s locked.
Rey: What sort of stupid exercise is this?
Luke: Now I see why Yoda taught like this. It’s fun!