Here are a couple of screenshots from the new 2.2 windowed mode. As you can see, it looks a lot like running the game in a terminal.
Here's the town:
And here's a cave level:
Here are some shots from the previous version running in a terminal. To make it look cooler, I'm using Cool Retro Term to bring the 80s Unix look.
This is some typical gameplay:
And here's the nifty new(ish) inventory menu:
While CRT can display colours, it's not quite flexible enough to show the field-of-view or unexplored squares so I had to turn those off for these. (I guess that's true to the whole retro look though.)
rxvt, it looks fine:
And here it is on a macOS Terminal with a light background: