NosChains

I think I might have figured out one way of doing chains of events over nostr

You have a server, with a reliable clock, that accepts NIP-98 where you can POST an event

1. Genesis event starts the chain, and must have a timestamp within the correct second of the server clock. Event can have tags, and replies in the normal way.

The server publishes the genesis event at a well known location.

2. A reply is posted to an event (with NIP-98):

IF the event validates and there are no other replies to the parent, the new event is published at a well known location Chain length increases by 1.

IF the event does not validate, or there already exists a parent event, the server gives an error, and does not publish the event

3. The latest event is sent to the relay network so that the latest event can be tracked, or with a pointer to an array of event ids in order. Using a kind 3xxxx and d=genesis event id

This could work with a regular pubkey, there might be a way to do mutli sig too, not sure.

Perhaps you dont need to check the timestamp also, as NIP-98 already does this.