Aliens Colonial Marines

Self-explanatory. You simply need to complete all 11 levels on Ultimate Badass difficulty in order to unlock this. All preceding difficulty trophies will also unlock upon completion of the game, but bear in mind that if playing on co-op, you will need to play each mission from the beginning. If you quit halfway through, your checkpoint progress will not be saved. Overall, this difficulty isn't too challenging but not exactly a walk in the park either on solo. Remember to keep the following in mind when playing through it:

• There's no time limit so take as long as you need. The checkpoints are fairly generous, however there are a couple of places where they are spread out a fair bit. Don't go rushing into combat.
• Everyone's play style is different but I found the Pulse Rifle, Tactical Shotgun and Battle Rifle to be all I really needed. Upgrade the Pulse Rifle’s secondary ammo to Firebomb to block corridors with fire, thus dealing serious damage to Xenomorphs and give it a red dot sight to allow for faster target acquisition. Stick with the default Arc rounds for the Tactical Shotgun to temporarily stun incoming enemies and upgrade the reload speed to allow yourself to get back into combat more efficiently. As for the Battle Rifle, I only used it to pick off enemies at a distance with the variable 2x – 4x zoom sight.
• When a Xenomorph is running towards you, make sure that you always back off whilst shooting it to ensure that it doesn't get any hits on you.
• Although you cannot see your health/armour and ammo count, you can generally tell how your Marine is shaping up. The Pulse Rifle has an ammo indicator on the actual gun and you can use the weapon selection wheel (hold ) to show the remaining ammo for the rest of your weaponry. As for your armour, you'll know when this has been depleted when you hear a shattering sound and see a temporary blue flash on the screen.
• Always pick up health packs and armour, this goes without saying but every little bit will help.
• When you pick up a Smart Gun, RPG or Flamethrower then keep it. This generally means there's going to be a section with a lot of enemies coming up and these weapons are great for crowd control. You can't replenish their ammo so just use it all up.
• I played through the entire campaign in co-op and found it to be a lot easier than doing it solo. Although the enemies will hit a little harder, the benefit you get from having an extra person(s) means that the mission won't be over until everyone has been killed. You can also be revived and jump straight into the action, you will receive a greater XP bonus at the end of the mission for having more than one person with you. Whilst not mandatory, it's a lot more beneficial to play through the campaign in co-op with at least one other person.