Rochard.

100% Gold Collectibles Found — Collect 100% of all gold collectibles
25% Gold Collectibles Found — Collect 25% of all gold collectibles
50% Gold Collectibles Found — Collect 50% of all gold collectibles
Bowling — Kill an enemy with an object shot with G-Lifter
Death from Above — Kill an enemy by falling on him
Death on Delivery — Kill 100 enemies using objects shot or dropped with G-Lifter
Electrifried — Electrocute a human enemy
Kiss Me Deadly — Kill a human enemy with another enemy's body
Pack Rat — Collect all upgrades
Say Hello to My Little Friend — Kill 2 or more enemies with a single exploding mechanical enemy
Second Amendment — Kill 100 enemies using the rock blaster
Speed Run — Complete the game in 3 hours or less
Unfriendly Fire — Kill a human enemy with deflected bullets
You're Fired! — Defeat maximillian.