Found this on Reddit it's posted for three years ago.
New world featuring 4 manors and one empty lot.
Sims can be invited to, or ask to attend, or hold a posh masquerade party event (featuring fancy new clothes) at these mansions (featuring fancy new furniture). The clothing is all masquerade ball stuff, but the furniture is mostly extravagant nonsense, not themed furniture sets for a fancy mansion. The scuba tank and Skydiving Machine from Sims Superstar, for example. The rest is all extravagant decor or stupid stuff like a platinum plumbob chandelier or a giant crystal llama or a Throne made of roses called "Every Rose Has Its Throne" or something silly.
The heft of the game pack comes from how in the early stages of the party, someone is...well, murdered. From here, you essentially enter into a game of Clue. You know the murder didn't take place in the room you were in. You know the murder didn't take place with an item that was in that room. And you know that the murderer wasn't someone who was in the room with you.
From there, Sims (NPCs and player alike) go around the house trying to figure out who the murderer was.
The pack includes multiple new death types. Things like "death from poison" or "death from giant indoor scuba tank" (a staple of any modern mansion) or "death from plumbob chandelier", which play into the game. The murdered sim immediately shows up as a ghost of their murdered death type and demands justice, which amuses the reaper, so he agrees to bring them back. Sometimes it'd be possible for the death to be entirely accidental (especially if the death is from the chandelier), and if you deduce properly, the ghost gets revived and then re-dies of embarassment.
It could feature some series staple NPCs like Ms. Crumplebottom! Mr. and Mrs. Crumplebottom hold an event, and Mr. Crumplebottom is killed by a chandelier, just like in the other games...wow! That'd be so cool.
I'm not sure how big of an appeal this would have but it's just an idea :D
https://reddit.com/r/thesims/comments/61nw0x/game_pack_idea_the_sims_4_murder_mystery/They said they've been working on this pack for at least a year... so who knows. Another pack that sounds like a one-time playthrough. (If it's true)
