There’s a pattern to a lot of events that I see go really well:

1. There is an almost-entirely-online community of nerds who care deeply about some niche topic.
2. An event organizer — who’s also part of that community — gently throws all the members of the community into a physical room with some chairs and maybe some food.
3. ???
4. Profit.

This is basically the core thesis behind most of the great events I’ve ran or helped out with.