Does anyone know whatever happened to the side project Kevin Wilson was working on called "The Delve"? Did official rules get posted somewhere? Does anyone know where these rules are?

Not an official answer here, but basing my opinion on his track record. My best guess is unless it's going to be released as a paid for expansion we may never see those rules. Kevin seems to always be "Too busy with new projects" to have time for any freebies.

The rules were pretty simple, IIRC. Basically you play as if it were vanilla, but draw dungeon cards from the deck to compose a larger "single" dungeon. Go as long as you can, that sort of thing. I forget what the rules for upgrading from copper to silver to gold were, but you could probably reverse engineer that part pretty easily.