Dungeon is the first level of the episode Formerly a Prince from Jazz Jackrabbit 2.
The Dungeon is pretty much a tutorial level, meant to get the player acquanted with the game's rules. As such the level's design is entirely linear and uncomplicated, with a few signs strewn about teaching the game's basics and almost no hazards despite the map's theme. The only enemies are Turtle Goons and Purple Bats which are hardly a challenge, as well as a few Tiny Dragons which are a bit more of a nuisance. At the end of the second area is the first boss fight of the game against Queen Earlong.
If you play the game on the lowest difficulty you'll be taken to a small tutorial area which teaches the game's controls before entering the level proper.