Calling it made in DOS is kinda false considering there's this thing called a graphics card
No, it isn't. DOS is just the operating system: you could easily make an OpenGL-accelerated DOS game. This, on the other hand, strictly uses software rendering. It really looks amazing considering the very limited resources.
EDIT:
I thought DOSBox emulated a Pentium 2 class
Not quite; the speed depends solely on how fast your host CPU is, or how many CPU cycles you've assigned. DOSBox also does not support anything newer than the Pentium's instruction set.
impressive through the software but on a 286 processor, performance would be horrible. this is why doom and wolfenstien had the graphics they had; they were meant to run on 286 processors
Lolno. DOOM requires a 386 CPU to be playable, and you really want a 486DX2-66 to play it completely smoothly. I don't even think it would start on a 286.