Alien Breed 2: Assault

Story related. Cannot be missed.
This is the first 'boss' of the game and you'll fight it near the end of Level 1. It has 2 stages, both of which are exactly the same. The fight takes place on a circular platform and all you need to do is keep shooting it until it dies. It has 2 main attacks. One is a blue slime ball that has a very large area of effect and severely damages armor if you have it equipped. You will know it is about to spit one of these at you as it will move its head back. Its second attack consists of the alien throwing explosive barrels at you. Both of these attacks are easily avoidable if you watch the alien before it attacks and run to avoid them.