FRAGNAROK wasn't made specifically for the DUNGENERATOR decks, but they are system-agnostic and can be used with it!
FRAGNAROK is a _very_ flexible, open system that can be run as a dungeon crawl or as a completely theatre-of-the-mind, "cinematic" game (like Monster of the Week or Blades in the Dark). Using the setup from FRAGNAROK and running the session with a DUNGENERATOR deck (and especially the PDFs of room prompts in the digital versions of the decks) works well!