The text object above.
Unfortunately there are no special plugins to generate ascii/roguelike games like that. You should be able to make a map of ASCII using the Array object and a Text object though. Use numbers to say what kind of tile is in each cell of the 2D array and then place a corresponding ASCII character.
I don't know how to randomly generate caves, but I might be able to make at least an example of static rooms for you if you'd like.