Drones make up the bulk of the Swarm's numbers and "manpower". Marines can be expected to encounter several dozen of these per mission, and possibly end up killing in the region of several hundred each over the course of a campaign.
Drones are weak in terms of durability, but fast, strong, and numerous. Their four massive claws can inflict horrendous injuries on marines unlucky enough to get hit. Being swarmed by Drones (especially if you have an empty gun and no backup weapon) is a surefire way to end up dead, no matter the difficulty level. A single Drone is only a minor threat to a marine and easily dispatched with gunfire or even a melee attack.
Very rarely, drones may spawn as nigh-invulnerable super drones that can absorb exceptional amounts of damage before dying. Perhaps the most efficient way to kill them is to deploy a Bullet Sentry to distract the drone. It will eventually destroy the sentry, but the sentry's explosion should also kill the drone.
There are also carrier drones, a rare drone variant that carries a Parasite on top of them. If the carrier drone is killed, the parasite will immediately come off and may attempt to infest marines. Several of those drones are encountered in Tears for Tarnor third mission, Oasis Colony Spaceport.
- Countering drones is easy; make your shots count, stick together, and cover your teammates whilst they're reloading or if they're being mobbed.
- Drones move more slowly if they're electrified by the Prototype Rifle or Tesla Cannon - neither of which will slow down or harm teammates, so use this to your advantage. Stunning a mob of Drones that are trying to gang up on a squadmate can give them breathing room to backpedal, reload, use items, and so on.
- Drones on fire, such as from a Flamer will be slowed down and often stop attacking marines and stumble around on fire. Alternate 'puffs' from the flamethrower with melee attacks to make short work of swarms of drones.
- Drones are very lethal on Brutal, as a single hit by their claws can reduce the health of weaker characters (such as medics) by almost half. They're also capable of withstanding a much larger amount of damage, making basic weapons less effective against them. It is highly recommended that at least one player carry a Minigun or Autogun to deal with drone swarms.
- Carrier drones are easily distinguished by the parasite riding on top of them. Avoid engaging them in melee or at very close range as the parasite that comes off upon the drone's death will likely infest the marine that was too close.
The drone's beta model/variant was intentionally supposed to be a recolored version of the original Alien Swarm's drone, however the Shieldbug, Mortarbug, Harvester, Parasite, and Queen did not exist in the original game, even though the appearance shares a similar style.