The Rats wear gas masks, as they once lived in toxic mines and tunnels. Over time they mutated, with some growing long claws and shrinking in size and stature, while the Rats as a whole have become cannibalistic. When they collect people to be sacrificed and eaten, midgets and other bandits are often on the menu. The masks have become a sign of their status, and they wear them now for ceremonial purposes.
Very much like actual rats, this faction will grab and make off with loot. This may lead to the player deciding if defeating a threat or pursuing a rat which has acquired a valuable loot item more worthwhile. Defeating a hoarding rat will result in a burst of scattered loot. Additionally, due to their cannibalistic nature, they can regain health by devouring corpses. They have a chance of equipping a shield upon picking it up.
- Assassin Rouf
- Dan, Lee, Mick, and Ralph
- Laney White
- Bloody, Crabby, Creppy, Dirty, Greedy, Sleazy, and Tipsy
- Allez Cuisine!
- I'm ssso HUNGRY!
- I can tassste you already!
- Another morsssel for the fridge!
- You sssmell delicious!
- Jussst another sssnack!
- Ssscream for usss!
- No mercccy!
- Food for the family!
- Your ssscent is intoxicating!
- Dribble the fat, mop it up, chew it down!
- Chew you up, ssspit you out!
- Tasssste the flesssh!
- Lick the chops! LICK the chops! LICK THE CHOPS!
- Can't hear youuuu!
- Ssswallow you whole! SSSWALLOW YOU WHOLE!
- I'm SSSSTARVING!
- You disssgusssst me!
- Ssssslice them open, ratsssss!
- Haven't had a bite in weekssss!
- Time to eat, boysss!
- Hate! HATE!
- Food comesss to ussss!
- Mouth watersss! Ssstomach RUMBLESSS!
- Ssscoff you down!
- Grab you, ssslice you, chew you!
- Not in the lab...Not in the lab! (Lab Rat)
- Look into my eyes (Lab Rat)
- Open your Eyesss (Lab Rat)
- Optic Blast! (Lab Rat)
- Windows to the SOUL! (Lab Rat)
- I sssee EVERYTHING! (Lab Rat)
- The FEAR! (Lab Rat)
- Omnomnomnumnumnum (said very rapidly)
On taking damage
- Who's cooking?! (when lit by fire or electric damage)
- What's cookin'? (when hit by fire damage)
- My SSSKIN! (when lit by fire or electric damage)
- My flesssssh! (when lit by fire or electric damage)
- What'ssss that ssssmell? (Lab Rat)
Stealing an item
- You don't need thisss anymore!
- Thanksss, brother!
- It'sss mine now!
- Corpsssse robbing!
- Thank you for the loot, brother!
- Throwing grenade!
- Grenade out, brothersss!
- Chew on thisss!
- I sssmell deliciousss! (when killed by incendiary elemental damage)
- One less...Mouth to feed...
- Not on an empty stomach...
- The food killed me!
- Killed...By a morssssel...
- Killed...By sssome dumbassss!
- Brothersss... kill them...
- Be ssstrong my sssonsss...
- I dessserved better...
- I can sssmell you...
- The goo killed me! (when killed by corrosive damage)
- Ssso who killed me!?
- Some players report that the hitbox for the head is a bit off, increasing the difficulty of scoring a critical hit.
- Rats move very frequently, making them very hard to kill. Using guns with larger spread or high rates of fire make them easier to kill.
- It is common to believe that fast action is the best way to get loot back from a rat. However, waiting a few seconds ensures the loot will not "break" out of the game and become unrecoverable.