Do you mean: "Is it necessary to have read the book first?"

If you have read the book, the plot is not (totally) identical in the game (thankfully), and some characters are added.

Incidentally, some of the comments on this very forum even have different views on how, for instance, Hercule Poirot is portrayed (compared to Agatha Christie's description).

And if you haven't read the book, you benefit from a complete discovery...

This orient express game was the starting point for any Agatha games that I just installed and got my hands of afterwards. I saw the movie first so I had an idea if where the game would be going, but it only does so midway. After that, a more extended story line is added, also they added a possible cliffhanger so it might be they continue the story even further at some point in the future :)

This story is one of the most famous ones, adapted to movies, musicals etc.. You won't miss anything, besides the games don't cover the earliest stories anyways.

Developers have made some changes to the whole story(that's probably good) and setting. Poirot appareance aside (this is no David Suchet) you play as a female detective for a while.

There are other Porot games, like ABC murders and London Case. This one is quite different - previous ones were more point and click like games. This one has controls more like standard third person games.
I did enjoy ABC Murders and The First Cases but London Case was just boring and I was tired of the game execution. The format just felt too tired and limiting.

Murder on the Orient Express tried to be better and mostly succeded. It had many bugs on release and felt quite rushed and underfunded.

Making these types of games is hard, I know that and there were parts of the game that felt the devs did care deeply. The game is worth playing if you are okay with better than avarage product. I wish they had more resources, the games would be much better.