Alien Breed 2: Assault

Missable
This trophy can be missed if you never use any Sentry Guns. Luckily there is a spot right near the start of Level 1 that is perfect for unlocking this trophy. Follow your way points until you have to enter the pipe junction room. A sentry gun will be sitting next to the small elevator you need to go down. Pick it up and then go down to the lower level on the elevator. Switch your item to the Sentry Gun and hold near the Power Point to install it. The sentry will have an opportunity to get around 10 kills here if you run straight to the Power Point and install it. Once that is done continue to do your mission objectives until you come back to this room with a 2nd valve. After installing the valve and turning on the 'Halon Control Pumping System' a 1 minute countdown will start. Aliens will continuously attack you during the countdown. As long as you don't kill any aliens with your hand held weapons and let the Sentry Gun do the work, the Sentry Gun should get more than 20 kills.