I am just now finding out about this and the first two are some of my favorite movies, though I definitely saw the first one waaayyyyyy too young. That image in the opening war scene where a random redshirt gets instagibbed by a shot from a mech cannon is seared in my mind forever. That was probably the most I have ever been disturbed by an image in any sci-fi horror, it isn't exceptionally gory the parts don't go flying or anything it's like his torso just disappears and the limbs drop straight to the ground in a very undramatic way and something about that really fucked up my 8 year old brain.