Trophies:

Bronze trophies

Team Veteran – Complete ‘Hydroponics’ in Co-op Assault.
Tooling Up – Purchase an upgrade (or witness another player doing this).
Saving the Day – In single player Story mode, save the game using the Intex Terminal.
Killing Spree – Within 30 seconds kill 20 aliens in single player.
Born to Kill – Kill 25 aliens in single player.
Vandal – Break the glass in a window (or witness another player doing this).
Just Browsing? – In single player Story mode, spend 30 minutes or more in the Intex Terminal menus.
Tank – In single player Story mode, take 500 damage without dying.

Silver trophies

Campaign Veteran – Complete all single player levels 1-5.
Fighting Light – Finish any single player level without using an item.
Ain’t Got Time to Bleed! – Finish ‘Interface’ single player level without using health packs.
Hard to Kill – Finish a multiplayer level with no player losing a life.
Knowledge is Power – Collect all logs through out the game.
No Stone Unturned – Find all ‘secret’ collectibles.
Elite Force – Without the player taking damage kill 50 aliens in single player.
Break a Few Eggs – In single player Story mode, destroy 50 alien eggs using melee.
Pure Pawn – In single player Story mode, sell 10000 credits worth of items or ammunition.
Deadly – Kill 5 aliens with one shot (or witness another player doing this).
Shocking – Stun 5 aliens with one stun grenade (or witness another player doing this).
Xenocide – In single player Story mode, kill one of each type of alien.

Gold trophies
Against the Odds – Complete all single player levels 1-5 on elite difficulty.
Break Out the Arsenal – Fire every weapon and use every item in single player.
Cash is King – Achieve a balance of 30000 credits or more.
Massacre – Kill 10 aliens with one shot (or witness another player doing this).
Electrifying – Stun 10 aliens with one stun grenade (or witness another player doing this).
Big Spender – Purchase the Damage upgrade for the Ion Spike.

Platinum trophy

The Completionist – Earn all Bronze, Silver, and Gold trophies.