>>25994
It's some kind of 2d sprite based graphics. It just simulates terminal graphics by using sprites that look like terminal characters.
The original library for actual terminals was Curses, which has since been replaced by NCurses. I can't tell you too much about it since I just started with it this week, but it should be possible to make DF-style graphics with it.
I was using it to make a Tetris clone just now.