Outcast puts players in the role of Cutter Slade, a former Navy Seal assigned to lead a team of scientists through a "string tunnel" to a parallel universe and help stop the growing black hole that is threatening life on Earth.

Players interact with over a thousand non-player characters (NPCs) in a 3D world infused with crisp graphics steeped in various types of terrain and lifelike weather conditions. The game development team used a proprietary artificial intelligence technology and an original music score performed by the Moscow Symphony Orchestra.

The artificial intelligence technology, GAIA (Game's Artificial Intelligence with Agents), gives each character a unique personality and creates reactionary behavior, making them respond in lifelike ways to the actions of the player. In addition, the game employs "procedural animation" to create realistic game character movements, a technique that blends two motion-captured sequences. Bump mapping gives characters' features and attire a more natural appearance.

Six regions (not counting Earth) of diverse climates and scenery serve as the basis of the alien culture and world of Adelpha. Snow-covered, forest, mountainous, watery, farmland, and desert climes blend together through an in-game travel process using Daokas, or portals.

Outcast runs two parallel storylines concurrently, one the quest to save the Earth from destruction from a black hole and the other, a tale of tyranny from which the Talans are attempting to extricate themselves. Slade must learn the terrain in order to get weapons and items replenished while at the same time searching for five "mons" in order to help the inhabitants.