The Caterfighter is a large, green, helmet-wearing caterpillar with three sets of arms. Each set of arms has a different weapon. After receiving a certain amount of damage, one set of arms will disappear and the next set of arms will start firing. After going through three arm phases, the Caterfighter will be killed.
The first phase is that it will constantly shoot mortars, three at a time. The second set has a plasma gun that fires two plasma balls next to each other. The last set of arms has a flamethrower that has a very large range.
Caterfighters appear only in the Pompeii chapter of the game. In most cases, they're treated like roadblocks that the player must defeat in order to advance.
- The Caterfighter has a significant weakness. If the player runs right next to the Caterfighter, all of its attacks will miss. This allows the player to kill it without a problem.
- Powerful weapons, such as the LM32 Rocket Launcher and MadDog Grenade Launcher, work best against the Caterfighter. It has high health, making powerful weapons almost required to kill it in a reasonable amount of time. In particular, a gunstack consisting of just powerful weapons works wonders when a Caterfighter appears.
- The first arm set's mortars can be avoided by fitting in between the large gaps between the mortars. The gaps are noticeable and the mortars are somewhat slow, giving the player enough room to dodge.
- The second arm set's weapon can be dodged by standing, letting the gun fire, then jumping over the projectiles while they're in the air.
- The best way to avoid the final arm set's flamethrower is to move far away from the Caterfighter. The Flamethrower has a limited range, which can be “dodged” by going past it's range.
- When paired with other enemies, the Caterfighter is a high-priority target. The amount of projectiles it spams during makes dodging other enemies' projectiles more difficult, increasing the chance that the player will be hit by a projectile, whether it be from the Caterfighter or another enemy.