that would be nice, but if it really is too too hard, i would be willing to settle for doom (doom is a good game anyways )
I’m Ripping The Sprites from the game though, so you probobly wont know they’re sprites.
Actually, you’ll be able to tell just by circling around an object and notice that they always face you. 
Your environments could use some work too.
Um… I’m Gonna Try to put directional facing in, I’m near to perfecting aircraft in the background that fight eachother.