Violent and features lots of grisly deaths with moderate blood. The tone of the movie is also quite bleak.
A man is shot in the leg.
Many deaths throughout.
One man stabs another, and blood is visible.
Threat of rape in more than one scene.
A man jumps back and accidentally rolls down a shaft into a huge fan and is chopped up. Tons of gore and blood spews EVERYWHERE. We later see all of the gore all over the shaft.
A man's head is snapped backwards by an alien and blood splatters all over another man's face.
There is a graphic scene where a dog has an alien inside of it. It starts to bark and writhe and cry and then the alien explodes out of its stomach. This is extremely graphic and disturbing as some of the organs disgustingly slide off of the aliens face. There is blood and guts all over the ground in this scene. VERY GRAPHIC AND DISTURBING.
The extended edition (the Assembly Cut) is rather gory with violent and at times gruesome death scenes that feature blood spurts and gore. The theatrical version however is more moderate in violence with fewer blood spurts and offscreen deaths.