Killed 30 enemies using only Traps

This one is extremely easy to get. There are various forms of 'Trap.' One of the first weapons you get is a Rivet gun. One of the special bullets is a Trap Rivet that you can use. You dont have to fire them onto the floor and wait for a Splicer to pass. You can just fire a few at the Splicers themselves and theyll die in a few seconds. Kill 30 enemies using this method and the trophy/achievement is yours.

Other types of Trap include Proximity Bombs and the Cyclone Trap Plasmid