So, almost every programmer used Doom as inspiration for new Projects, right? So Doom and other classic MS-DOS game were played on something like Command Prompt. How do you display images in Command Prompt without using System.Windows.Forms? By the way, I don't accept add-ons. (It doesn't have to be 3D)
Games like Doom ran in 16 bit real mode under DOS. In this environment, there were system calls, called interrupts, that you could call to switch the display into several graphics modes.
The most popular at the time was mode 13h. It was called this, because you called interrupt 10h (h specify that this is a base 16 number), with register al loaded with 13h, ah set to zero. 16 bit assembly going something like:
xor ah,ah mov al,13h int 10h
Once in this mode, you could write directly to graphics memory that started at offset 0xA0000. See the wikipedia article, or many mode 13h tutorials on the web for how to do this.
Do note, to do any of this today, you need to have a compiler capable of outputting 16-bit code, or an 16-bit assembler.
To be clear, I answered to provide some historical background on your question, and to show you how you could do this sort of programming still today, if you wanted to, for purely educational purposes. Please note, this is not possible with C#.
Doom itself had little to nothing to do with the command line. They actually had APIs to do graphics back then, much of the use written ones use the method Stephan explained. I've also seen command line graphics done in C++ though, but it had to do with lots of code. None of this is possible in C#.
I also would not advise such bland questions on this site. Please explain more next time!