Murder at Midnight, as a series, is the direct forefather of the character-oriented roleplaying scene within the larger roleplaying community in Facepunch's Fast Threads, resulting in the thriving community we now know as the Facepunch Character RP Group, starting with everyone's favorite, Starpath.
This game specifically, the 7th entry, or "season", in the series, takes it back to its roots, abandoning the restricting and lethargic story which plagued the later three seasons, and returning to the more dynamic and liberal system used in its first three seasons. As the series page linked above explains the rules quite clearly, there is no need to repeat them here.
Despite the move back to the original system, there are sprinkles of a story here and there, something being quite obvious, displaying that this "season" doesn't exactly take place in the same world as the original seasons, something which is confirmed with each passing lore post. Players can choose to engage in this story by interacting with televisions, radios or newspapers, in an attempt to see how this seasons connects with the last couple, though for the most part, the game master just spells it out. Because of its different connections to the past seasons, which includes its proper classification as a character RP, its season isn't indicated.
This will be filled in once the game is finished.
Same as the events section.