So i want to develop a game like Doom 1993 with a jungle theme. I just want to ask your opinion if it is better to use 2d sprites on 3d perspective or create a 3d environment and then use 2d sprites for character and enemies. (what i mean by the second option is basically create the terrain in 3d and then just put 2d sprites in it). Or maybe there is other good way to develop this type of game?
Yes, its better to use 3D terrain with directional sprites. Lock the camera from moving up and down and use raycast for player interaction. you can also look into this shader, its free. Pixelation | Fullscreen & Camera Effects | Unity Asset Store