The main game element is similar to Clue: you are trying to deduced who was murdered, at what time, in what car, the motive, and the murderer. One twist is that, rather than asking people questions about the cards they have in their hand, players exchange cards based on actions that occur in each car. Players must also strategize how to spend their time on each turn - there is a limited number of moves that can be made based on how long the train takes to get from one station to the next. Each card appears twice, which means that seeing it once doesn't necessarily rule it out. To determine the time the crime happened, there is a separate deck of cards that operates similar to memory - you flash through the cards quickly and try to determine which one is missing (time cards are a set of 3). Also, in starting the game, not all cards are yet in play. Passengers board the train at two stops, at which time players have access to additional cards.
Set up and first play with a rules run-down is a very long experience. With 4 players, all seasoned board game aficionados, we had to keep revisiting the rules. The entire game play took 3 hours. Even if we were all familiar with this particular game, it is unlikely to be playable in less than 2 hours. The best strategy is to keep track of where you saw the cards, to whom you passed cards, and who passed cards to you.
Esthetically, the board is beautiful and the cards are well-appointed. Each player has a "ticket book" to hide his/her notes and deductions, which are nice. The ticket book also has a run-down of the mechanics of each train car for reference, which comes in very handy.
If you like light-hearted, easy games, or to socialize during games, Mystery Express is not recommended. It's best suited for people who enjoy logic puzzles, long games, and strategy. It requires a great attention to detail and multiple moving parts to achieve the correct solution.