Monster pop up and shoot

Hi im making a game like duke nukem,doom,quake and i was wondering how i could make the monsters come in from some random direction and shoot you.

thx in advance,

uhhh doom and duke nukem look different one is a fps which aperently you can’t do or you can and it will take decades to do and duke nukem is side ways and they dn’t come in randomly so i’m not sure what you are aiming at

there r aliens that just walk from the left and right sides of the screen then they stop and shoot at you

ohhh just have it do x +5 then X-5 … and have an invisible mc that if they hit it they turn around and fire

I bet Duke Nukem: Forever was going to be an FPS.