Descent as a game series prides itself on being Nintendo Hard. Most of that difficulty comes from robot enemies purposely-designed to give the player hell.
Descent 1
- Red Hulks (a.k.a Advanced Hulks, Heavy Hulks, or Super Hulks) are Elite Mook versions of the brown-colored Medium Hulks. They're the only robot in the game with Homing Missiles and nearly enough health to tank a direct hit from a Mega Missile. In most places you find them, they won't be alone; there will be other robots in the room with them. So you have to either focus on the Red Hulks while the other robots are firing at your back, or focus on dogfighting the other robots while dodging the Red Hulks' Homing Missiles. The game also loves throwing them at you in tight corridors where there's little to no room to dodge their Homing Missiles.
- The Class 1 Driller comes equipped with the Vulcan Cannon, the nearest thing Descent has to a Hitscan weapon in a game where every other weapon fires Painfully Slow Projectiles. Because the robots in this game don't lead shots, when the Driller fires, it's deadly accurate and does a lot of damage, even on easier difficulty levels. If one is encountered at close range, it's basically impossible to destroy it without taking damage since they open fire faster than you can react. They also have tougher cloaked versions in later levels. Both versions of the Class 1 Driller will often be found paired with Red Hulks and other Demonic Spiders. If you see an Invincibility Power-Up, these robots are most often the reason you'll need it.
- Advanced Lifters are faster, quieter cousins to the Medium Lifter. They're also smaller, which means you'll often get ambushed by more of them at a time. They're most often found partnered with Class 1 Drones and Secondary Lifters to provide diversion and fire support, and in levels with a lot of red or orange wall textures that these robots can blend into.
- Heavy Drillers are the Elite Mook upgrade to the Class 1 Driller. Their Plasma Cannons aren't hitscan like the Class 1 Drillers' Vulcan Cannons, but they still do a lot of damage, and the Heavy Driller loves to spam them like crazy. The Vertigo Series has a Class 2 variant that also fires returning homing plasma.
- The Class 2 Platform Robot comes in two variants: a pinkish-white version that fires lasers and a green version that spams Concussion Missiles. The green version is the day-wrecker. If a Platform sees you, it will sling anywhere from three to a dozen missiles at you at a time, enough to pummel your shields to zero if you don't see them coming and get out of the way. You'll find them in large rooms where you're dogfighting multiple robots at once (and thus less able to keep track of Concussion Missile swarms flying at you) and in close enough quarters that you're likely to take Splash Damage even if the Platform misses.
- Fusion Hulks are the game's Boss in Mook Clothing, and the one non-boss robot that's tougher to kill than the Red Hulk. Their name comes from the first game's BFG, the the Fusion Cannon, which fires projectiles so large that any near-miss still counts as a full hit and rips 60 points off your shields (you spawn with 100, and 200 is your maximum). The saving grace is that this also makes firing through grates and around corners just as problematic for the Fusion Hulk as it is for you. And it's often encountered in places where there's a grate or a corner you can use as cover.
Descent 2
- The Lou Guard is the Red Hulk's Descent 2 Expy. Unlike the Red Hulk, the Lou Guard is a dedicated ambusher, often found where it can surprise the player. The first one you meet introduces itself with a Homing Missile sucker-punch to the face the instant you open the door to leave your Respawn Point.
- Diamond Claws are faster and tougher than their predecessors, the Medium Lifters. They're designed and positioned in such a way that there really aren't a lot of options against them that won't also hurt you, too. If you hit them with energy weapons, they fire back with homing Smart plasma. Being melee bots, they're constantly moving toward you; most of the time you fight them, they're close enough to catch you in your own Splash Damage if you use missiles or Gauss on them. Finally, when you do kill them, they use the new weaponized-explosion mechanic to get one last hit in. They have cloaked versions, but the normal versions are colored to blend in with the most common rock wall textures in the game; either way, the only way to know they're around is the distinctive sound they make when they attack. Descent 2 loves using these things in ambushes, so they'll be a thorn in your side for most of the game.
- Sidearms are huge, easy targets. Their phase-pulse cannons do a lot of damage, but are otherwise easy to dodge, and dodging them will usually also dodge their Flash Missiles. The Sidearm Modulae they spawn, however, are tiny, hard to see, and harder to hit, and each one is all too happy to spam Flash Missiles at you on sight. A few of the most sadistic ambush traps in Quartzon consist of a cluster of Sidearm Modulae behind a secret door or disappearing wall.
- The Green Spider found in later levels takes the place of the Class 2 Platform as the game's chief spammer of Concussion Missiles, but retains the Red Spider's ability to spawn Goddamn Bats to continue harassing the player when they die.
- The Seeker is another tough robot found in Quartzon that fires Mercury Missiles. On Trainee and Rookie difficulties, robot-fired Mercury Missiles are very slow, and the Seeker only fires one or two at a time. On Hotshot difficulty, those missiles are moving much faster, and the Seeker will be firing more of them at a time. On Insane, the Seeker's Mercuries are streaking as fast as yours are, and its spamming them like mad trying to beat the hell out of your shields.
- Omega Defense Spawn are small, fast-moving suicide-bombers that take a lot of damage to kill. When they explode, they blow up with enough force to punt you across the room...and, potentially, into another Omega. Camoflauged Omegas are a common occurrence in the levels after Quartzon, though they prefer to run away from you and drop bombs rather than kamikaze-rush you. Of course, they don't try very hard to avoid ramming you by accident, and they still pack a hell of a wallop when they explode. In some levels, the blue, yellow, and red keys will be carried by camo Omegas, forcing you to chase them down and kill them in order to complete the level.
- The BPER Bot comes with a faster version of the Sidearm's phase-pulse cannon, and they're often seen camping corners in the later game because of how quickly they can shred your shields with it. The BPER Bot is also another robot that dies in a high-damage explosion in an effort to take the player out with it.
- The Energy Bandit is a melee robot that drains your energy and shields instead of simply damaging you. They're as fast and tough to kill as the Diamond Claws, though thankfully they don't fire homing plasma or explode violently. They'll drop the energy they stole from you when they die, but you're not always guaranteed to get back all of the energy they took.
- The Boarshead takes over for the first game's Fusion Hulk as the deadliest non-boss robot in the game. The Boarshead fires Smart Missiles and a gatling Plasma Cannon, both of which are capable of tearing a player to shreds on sight. This robot has the honor of being the only robot with a danger level of "extreme" in the briefings.
- The Vertigo Series levels add the Maximum Amplified Xenophobe, or MAX. It's another Expy of the first game's Red Hulk, only now it fires homing Flash missiles like the infamous Ice Boss.
Descent 3
- Stingers are tough, fast-moving robots that spam missiles at you at range, and charge to swipe at you in melee if you get within medium range. The most common ones seen are the red and blue "police" models that fire Homing Missiles, though a green "sewer" version that fires Concussion Missiles can also be found. They have a black Elite Mook version that's tougher, faster, and fires two Homing Missiles at a time.
- Tailbots start out easy enough to kill, having low health and a rather useless EMD gun for a weapon. Their first upgrade, though, makes them tougher and equips them with Concussion Missiles, making them a more credible threat to the player. Their Elite Mook version is tougher still, and fires Frag Missiles that can kill you instantly if you're too close to a wall.
- The Gyro is The Goomba in this game; it's the first enemy the player encounters in the game, alongside the Orbot. Its red Palette Swap, however, trades in the laser for a Napalm Gun, and it will hose you down with it the moment it has line-of-sight to you. And it will not stop until one of you is dead.
- There is a tank-like enemy present in some of the later levels that fires mega missiles. Notable as the only non-boss enemy to use these weapons in the entire franchise.
