The Last Express is an obscure and basically unmarketed point and click mystery adventure game, which is sad because it's honestly one of the best put-together and effortful adventure games I've ever come across. You'd only really have heard of it if, like me, you dug through the files of Myst back when it came out on CD and saw the trailer for this game.
The author does a better job summarizing the LP, so I'll let them speak for themselves:
This, my friends, is one of the best interactive mystery-adventure games I've ever played. The Last Express is a video game created by Jordan Mechner and Smoking Car Productions, published in 1997 by Interplay and Broderbund. If that last one sounds familiar, it's because it should: Broderbund also published the original Myst, Where in the World is Carmen Sandiego?, and Prince of Persia. Jordan Mechner should also be a name you recognize, as he's the brains behind the entire Prince of Persia franchise.
The game is set on the Orient Express, only days before the start of World War I. It's one of the few video games that attempts to simulate real time realistically, but despite very positive reviews and critical response, the game sold poorly due to the entire marketing department quitting weeks before the game was released.
[T]he game is set on the Orient Express before World War I in 1914. The game begins in medias res as our avatar, Robert Cath, boards the Orient Express to meet a friend. Once on the train, we quickly discover that the Orient Express is a hotbed of intrigue, danger, treachery, and lies, and we must do all we can to survive and discover the truth behind unfolding events. I can't reveal more than that because this game is really good at drawing out the mysteries and allowing you, the player, to speak with other characters, investigate their possessions, and learn things for yourself.