Natural Selection 2 is a Multiplayer Indie Real-Time Strategy/First-Person ShooterHybrid, which pits a bacterial Alien collective known as the Kharaa against a team of Space Marines. The Bacterium has infested a Human ship/installation, slaughtering everyone on board. Frontiersmen are dispatched to take it back and destroy the infestation. The Frontiersmen wield all sorts of high-tech weaponry against the vicious Hive Mind of the Kharaa, who can evolve rapidly into deadly new lifeforms that can teleport, walk on walls, smash through the heftiest marine defenses or spread their bacterial infestation across the map. Both sides will stop at nothing to utterly exterminate the other.Natural Selection 2 is the sequel to a 2001 Half-Life mod, which followed the same basic premise. However, it has been several years since the beginning of the Marina-Kharaa conflict, and both sides have developed and lost abilities, creating a significant contrast between the two games. Both were developed by Unknown Worlds Studios. NS 2, however, is not a mod - it runs on an independently-developed engine.
The Natural Selection series contains examples of:
Art Shift: The Kharaa have undergone a significant art shift between NS 1 and NS 2. In the original, they appeared far more fleshy and organic. By NS 2, they have become darker in color, with the exception of the Fade, which looks almost the same as it originally did. They have also gained significantly more armor on their heads and bodies. The Marines have also received an upgrade - their armor and structures are much more high-tech and smooth, contrasting the blockiness of the original.
Assimilation Plot: Despite the Kharaa's modus operandi being 'assimilate other species and weaponize them,' care is taken to avert this. Marines cannot be assimilated by the bacterium, thanks to the wonders of Nanobot technology.
Aura Vision: The Aliens' hive-mind gives them the ability to see friendly lifeforms and structures through walls, and with the proper upgrades or a parasite, marines as well.
Air Vent Passage Way: Almost every map has at least one of these for Skulks, Lerks and Jetpackers to use.
Adaptive Ability: The Kharaa are incredibly versatile and adaptable. No matter what the Marines try to gain an edge, they seem to have a way to counter it, and often they adapt the marine's tactics in some way, such as with the Harvester, which functions in the same way as a Frontiersman Extractor to gather resources.
Breath Weapon: The Gorge defends himself by spitting slime at his enemies. It's surprisingly effective at discouraging marines.
Blood Knight: The Fade, which is said to be one of the most intelligent Kharaa lifeforms, seems to enjoy his job more than any other lifeform does, and shooting him just makes him mad, as the Fade Reveal trailer shows. You won't like him when he's angry.
Bizarre Alien Biology: The Kharaa feature numerous bizarre traits. Special mention goes to the Skulk and Gorge, who share a trait - their lower jaws are actually two separate appendages, connected by a piece of stretchy flesh that acts as the bottom of their mouth.
Continuity Nod: Several of the maps are updated shinier versions of maps from the original NS.
Cool Tank: The Onos and Exosuit qualify for the Kharaa and Marines respectively.
Cherry Tapping: As Alien, the Skulk, Lerk and Gorge can Cherry-tap with Parasite, Spike and Spit respectively. The Marines can cherry-tap with the knife or pistol, or the claw when in an exosuit.
Horn Attack: The Onos uses its' center horn to gore marines and toss them around like ragdolls.
Technology Porn: The Marines' structures and armor are beautifully rendered and smooth, unlike in the original, where they were highly blocky and heavy-duty.
The Corruption: The Kharaa spread their infestation across the surrounding area, and assimilate other species into their genetic fold.
Evolution Power-Up: The Kharaa thrive on this trope. Changing life-forms? Evolution. Getting an upgrade? Evolution!
Evolutionary Levels: The Kharaa, again. Each 'level' qualifies as a lifeform. The Skulk and Fade appear to be related in some way, as they both share bladed limbs and a long muzzle with sharp teeth, and their movement animations are strikingly similar.
From a Single Cell: How a Kharaa invasion starts. Apparently, even a small spore is enough to begin a serious infestation, as the Bacterium reproduces quickly and reacts viciously to threats.
Finishing Stomp: The Onos can throw marines to the ground with an unlocked ability, at which point he can brutally crush their skull beneath his might spacecow weight. The Kharaa don't mess around, folks.
Gatling Good: The Exosuit has a chaingun on one arm that can reduce any hostiles to mush in seconds. It can be upgraded to have another replace its' rather useless claw.
Goomba Stomp: The Exosuit can goomba stomp eggs, crushing them beneath its' weight.
Gameplay and Story Segregation: Despite the game's official Wiki stating that Fades have been observed warping through solid matter, they cannot do so for obvious reasons.
Glowing Eyes of Doom: All of the Kharaa have had their eyes turned to an evil glowing orange color by the Bacterium.
Humongous Mecha: The Marines can eventually research and purchase an enormous Exosuit with dual miniguns. It's as awesome as it sounds.
Hive Mind: The Kharaa share one, which is one of the major reasons they are so deadly.
Idle Animation: The Aliens all have idle animations which they play when you're standing still. The Skulk and Fade pick their teeth with a claw, the Gorge yawns or licks at a decaying tooth, the Lerk stretches it's wings, and so on.
I Shall Taunt You: The Marines can make snarky comments at the Aliens. The Aliens all have the ability to chuckle, and each lifeform has its' own taunt.
Keystone Army: The Kharaa depend on their Hives to live. If their Hives are destroyed, they all die instantly, along with the Infestation across the ship.
Kill It with Fire: The marine commander can research a flamethrower for his team. This weapon is great to scare away light enemies (such as skulks). However its main use is to clear out alien infestation and their organic buildings.
Lightning Bruiser: With the right upgrades, the Onos is a lightning bruiser, able to rush into an enemy base and completely wreck it in minutes.
Mouth Cam: The Skulk, Lerk and Gorge all play from a mouthcam perspective.
Organic Technology: The Kharaa are adept at this, to the point that they're a match for the best equipped, best trained troops in the TSA without ever using a single piece of technology.
One-Gender Race: None of the Kharaa appear to have a gender. Justified, however, given that the lifeforms in the Kharaa have been optimized for their roles, and the hive makes reproduction obsolete.
You Will Be Assimilated: Every single playable lifeform, and some of the structures, are extraterrestrial species which have been assimilated by the Kharaa. The Marines, fortunately, cannot be assimilated, as the nanobots in their bodies kill the bacterium if their suits are breached by it.
Power Armor: The Exosuit is a cross between Power Armor and a Mecha. The Marines could also use Power Armor in the original NS.
Pocket Dimension: The TSA speculates that the Fade is able to access one, explaining its' ability to teleport around. The Fade can also send a large group of enemy soldiers/structures into the same zone for a short period of time, rendering them harmless, with the right upgrade.
Plant Aliens: Some of the structures the Kharaa can build in both games strongly resemble plants.
Preorder Bonus: Players who preordered the game receive a special Deluxe suit of armor for the Marines and get the official soundtrack and art for free. Players who preordered the special edition received the same, along with a suit of black marine armor. The Developers are debating on whether to include similar skinks for the Kharaa as part of the deluxe edition bonus.
Slave Race: Technically, every playable lifeform counts, given that all of them have been assimilated into the Kharaa by the Bacterium. It's unknown which, if any, were sentient when they were assimilated, but the Fade in particular is speculated to have been.
Scenery Porn: The Kharaa's infestation and structures, while squicky, are beautiful in their own, odd way.
Flash Step: The Fade uses an ability called shadow step to move around quickly. It can be upgraded to last as long as the Fade's energy pool does.
Trailers Always Lie: Subverted in that most gameplay features shown in the game's promotional videos are included, but disappointingly, it is not possible to impale an enemy's marines and redirect his attacks on his allies as in the Exosuit reveal trailer.
We Have Reserves: Either the marines are somehow being saved from death when they die, or their commanders are EXTREMELY liberal about how many lives they're prepared to lose to hold onto the installation. Justified with the Kharaa, who are simply assimilated back into the bacterium and born again as a new lifeform when they sustain fatal damage.
Worker Unit: The Gorge falls under this category, being the Kharaa's engineer/medic, as his healing spray can speed up the building process for structures placed by the Alien Commander, and he can place clumps of infestation to act as a barricade or grow spikey plants that send barbs into nearby marines.
The entirety of the marine team also falls under this category, given that they need to build structures their commander places, unlike the Kharaa, who's structures will grow without aid from a Gorge, albeit slowly.
The marine commander also has access to a robotics bay later in the game that builds directly controlled units called MAC. They are completely automated and will build and repair anything near them.
Zerg Rush: If the Commander can coordinate his team into a rush, they can end the round in record time by swarming the enemy base and destroying their Command Chair/Hive.
This is pretty much justified with the Kharaa, since they are an alien race with small, very fast, four-legged, wall climbing units known as skulks, who are extremely weak early-game and must work together to take down marines.