"Someone aboard this train is not what they seem. The person who k1lled Physicist Kirbo is... YOU!!!" This is Utility, a bright waddle dee who hails from a world of infinite flooding. Mystery on the Waddle Dee Express is a short, murd3r mystery game @ItsOli23TEST is making for Spooky Month. Each round, the k1ller is chosen randomly, and the player has to figure out who it is. You can signup your OC on the original project (found above). If you don't know what to write, there's an example sprite in the project.
Of course, credit to @ItsOli23TEST for the original project, and Kirby and the Forgotten Land for the music.