A really intriguing theme! The concept of delving into the unknown below a city has its own connotations and threats beyond a "dungeon". I like the inclusion of a costly magic system, an Advantage mechanic, and the implementation of character archetypes to follow.
Viewing post in Tunnel Crawlers jam comments
Oh I saw the Advantage/Disadvantage mechanic in quiet a few others now. Looks like some ideas are floating and echoaing nicely within the Jam. I was Inspired by the The Midnight Chimes to include Classes.