Ryan Veeder's Agatha Christie's the Murder on the Orient Express

If you've played Ryan Veeder's previous "adaptations" of existing work (The Lurking Horror 2, The Little Match Girl) it won't be a surprise that this only connects to the original murder-mystery in the loosest sense. Yes, there is a murder, yes, you're the great Belgian detective, yes you start on the Orient Express. Beyond that, anything goes: Poirot can exit and enter the train at will, it stops at Calais, the great pyramids are now in Morocco, Vienna is famous for its canals. Poirot's personality is hilariously dialled up to 11, a fearless, hyper-competent egotist eager to tell other characters (and the player) how great he is. Gameplay-wise, there is no mystery to solve, just "clues" (i.e. points) to collect by exploring, examining everything, and talking to everyone thoroughly. A small number of traditional inventory puzzles and locked doors are sprinkled about to keep traditionalists happy. You can eventually "accuse" any character in the game to get one of dozens of unique, lengthy, very well-written endings.