Natural Selection 2

Like its predecessor, Natural Selection 2 features two opposing teams of players, Kharaa (Aliens) and Frontiersmen (Marines), seeking to destroy the other's respective base. While the two teams have the same essential goals, gameplay for each team varies drastically. Marines largely rely on guns and other pieces of technology to annihilate the alien presence. Aliens rely primarily on melee attacks.

Certain alien lifeforms can walk on walls, fly, and dash forward quickly. Players have a currency system which they use to buy better equipment or evolve into higher lifeforms.

A game engine originally dubbed Evolution was developed specifically for the game. It has since been renamed Spark. The game engine utilizes the Lua scripting language for game logic, allowing for easy expansion of the game's mechanics. Physics support is provided by several third-party libraries.

The game was announced in October 2006.

The game sold 144,000 copies in its first week, earning over $1 million. As of February 26, 2013 the game has sold 300,000 copies.

The review aggregator Metacritic shows generally favorable reviews, with a Metascore of 80.