Game idea?

I haven't played DND much cause I don't know much about it and don't really have people to play with but I like writing ideas down ssooo for any tired Dm's looking for a cool mystery maybe slightly thriller champagne idea here ya go??

Champaign where the party has no memories. Their given a sheet thats basically name, rough age estimate, description.

And randomly given different items. They must figure out who they were from clues around the town and passers by who know and reconize them from saving the town some time back. As their making discoveries they will unlock memories of small things. Items they find, places they've been to, feel tied to weapons they once used meaning maybe they have to swap weapons to figure out which feels the best using riddles and poems to figure out who they once were. Their backgrounds and find out what happened.

At the very end they reach a (insert final boss area) and during the battle half way through they find themselves being unable to hit the beast. Arrows missing, magic rebuffing or hitting the others, limbs movin on their own and unable yo do anything about it.

They find out towards the end that the big bad is actually an necromancer. Had killed them (howevee way) sepritly after they sepirated from their one misson to save various towns from different things it sent out (one shot to be played months before this. But.. Changing who plays whos character. Exsample X plays Y's character insted of Y)

They start to peace together that their actually the necromancers powns that they revived. Theh must find a way to somehow break the bond and let their spirits be free or lose and find themselves lost trapped behind bodies they no longer control