i have played your demo in the past, and nex time it would be cool if you could make enemies less "perfect"
caus when you encounter one, it was shooting at you continuously and very precisely, he hitted you each time and very hard or impossible to strafe to avoid the shots and shoot at same time.
Next time make ennemies shoot each second or 2 seconds, make them reload also and make them less precise so they can miss the player sometimes.
you can also make one with a railgun that you heard the osund before he shoots, the player woud have to hide during the shots, and 5 seconds after the continuous shots, the ennemie would have to reload and the player could now attack him.