In regular Clue, you set three cards aside at the beginning of the game, and the players try to deduce what those three cards are by figuring out what cards are in each others' hands.
In Death Clue, each player is dealt three cards and the name of ANOTHER player, tries to deduce what THAT player is holding in their hand, and is required to lie (pass) when THAT player asks for clues. Goal is to "kill" THAT player by guessing their hand, but you can also "kill" whoever's hunting you. Everybody (usually) survives to the endgame and the endgame is pretty quick.
"Resistance: Avalon" is my Sunday group's go-to game. It's fast, easy, a little bit of strategy and lots of persuasion. For us (~5 or 6 players) it tends to be one-sided, and I'm pondering how to change that.
Current notion is to hybridize it with Death Clue while preserving the talky/cooperative aspects. (Don't know how. Might not be possible.)