This is such an excellent idea, that I'm amazed it's taken this long to get made (it's been ticking along for quite a while apparently). The original Jumanji did a "the game affects the real world", and the TV series had a "transported to the jungle" aspect, so the "dragged into a game", ala Tron, is a perfect match for the Jumanji canon. It's also not a genre that sees much love in film form, being restricted either to a cartoon/animated trope, or the whole LitRPG/GameLit subgenre. (I reviewed a few recently if you want to go back through the Books archive to locate them.)
The titular boardgame, washed up previously on a beach at the end of the first film is collected by a video game nerd, and, having spent an evening observing him updates itself to a little cartridge, for the nearest handy games console. The Alan Parrish scenario repeats itself, and then the console sits around for twenty years. It's finally found by a group of students disparate enough for the development of sufficient plot who are brought together with the power of detention, and they get themselves dragged into the Jungle world of the Jumanji game.
And of course, they're transformed into their game characters, played by Dwayne Johnson, Karen Gillan, Jack Black and Kevin Hart. Which is most surprising to the girl who finds herself in the body of Jack Black. Who I think has found his perfect niche playing overly dramatic, body-switched teenage girls. I don't often like him, finding his overly dramatic screechy style painful, but it works very well here. Also impressed by Johnson who has spent his career with people going "I didn't know he could act!" He does a delightful version of a nerd impressed that he suddenly looks like Dwayne Johnson, while sill doing a decnt version of a child who doesn't quite know how to behave. Gillan and Hart are also fun, though aren't quite as standout. You do get the impression though that the cast had a great time filming it.
Since they're trapped in the game, we now have to deal with game mechanics, such as lives, NPCs and similar. It's rather fantastic fun, and the film uses it for a fair bit of comedy. It's also great to watch the cast find ways to hack the game, making use of exploits or common tactics as a nerd typically would. The only thing missing is save scumming. I can imagine Jumanji not approving of that. It also allows a few bits of trickery like cutscenes, all of which add to the atmosphere. And the game provides us with a brilliantly over-the-top villain in the re-appearing Van Pelt, here played by Bobby Cannavale as a mind controller of animals.
In terms of film mechanics in general, it also performs very well. It loads and fires an impressive number of Chekhov's guns, has some rather well assembled action scenes and the set pieces are great.
Overall, excellent film, which I enjoyed enough that I'm probably going to have to go back and watch the original.