Well, looking up the etymology for "crawl" (emphasis mine):

> ***crawl*** (v.) 1200, creulen, from a Scandinavian source, perhaps Old Norse krafla **"to claw (one's way),"** Danish kravle, from the same root as crab (n.1). If there was an Old English *craflian, it has not been recorded.

Then, the definition of "clawing one's way":

>***claw your way (somewhere):*** to move forwards with difficulty, especially by using stiff curved fingers to remove the things that are in your way

This would likely meet the idea that a "dungeon crawl", while initially thought to suggest a snail's pace, might actually mean "fighting your way" through a dungeon.