Quoting: Almafeta
From Doom 64:
*Arachnotrons were upgraded, having twin plasma rifles instead of a chaingun. (A doomrl 'Arachnotron Mark II'?)
I'll make this clearer. The Doom 64 Arachnotron had dual plasma guns, both at the front. However, unlike the original Doom Arachnotron, it fired in 8 round bursts (4 from each gun) instead of full auto fire.
*Rottweilers. Undead, demonic dogs; they are to pinky demons what pistol soldiers are to chaingunners.
I didn't see this in Doom64 at all. :\
*The Unmaker. The damage done by this weapon varies based on how 'demonic' the target is; former humans take little damage, normal demons (the lost soul, the demon, the knight and baron) take full damage, partially robotic demons (the Cyberdemon and Arachnotron) take mild damage. Powered by corpses of humans.
This is the Doom bible version. The Doom 64 version was just a laser gun powered up by demonic keys.