Ive been thinking of having the players start as prisoners, convicts, criminals. Either real criminals or unjustly convicted. Then forced to go on the mission/adventure in exchange for freedom. Its better than life of hard labor, a death sentence, or even prolonged imprisonment.
Like the "Suicide Squad" if you are familiar with the comic, Escape from New York, Dirty Dozen. Even the Ghost Tower of Inverness used this.
Something different than "You meet at the Inn/Tavern".
They don't all have to be hardened criminals. (but some might)
Other than the start of the party & their background(possibly some personality traits also) not much would change about the adventure.