Character's Last Will and Testament Rules
Characters can have a will naming an out of game family member as a beneficiary of their wealth. If the rest of the party fulfills that will, then the player's next character receives that wealth in starting experience.
If dead character has an unfulfilled will and is not buried in a ceremony on consecrated ground, there is a chance that the character's spirit will rise as an undead spirit of level and abilities appropriate to the character and their death.
I'm thinking about these rules in the context of a city/megadungeon campaign with a large player community.
There's always a question of what level to start a replacement character. The common OSR answer has been to start at 1st level, while more recent styles of play replaced characters at the current level of the campaign.
It's also always a bit odd how party members fight over the belongings of a deceased former friend. Together, these rules would give a party in-game reasons for treating their dead comrade in a more familiar fashion.
Of course, parties are free to ignore these rules and the consequences. In fact an evil party, with an evil priest, might not be adverse to another undead creature in the dungeon.
What do you think?