X-COM: Terror from the Deep

X-COM: Terror from the Deep is the sequel to UFO: Enemy Unknown (or X-COM: UFO Defense in North America), and the second part of the series. It was developed and published by MicroProse. Its interface is nearly identical to its predecessor, as is its graphics technology. Terror from the Deep was recently released on Valve Software's Steam platform.

In the original game, the player was tasked with defending Earth from invasion. Now, forty years after the first alien war, that lasted for three years, was won, a new alien menace begins to emerge from the deep oceans. The game plays out underwater, with base-building and combat all being submerged beneath the waves. The only time in fact that the game moves onto dry land is for terror site missions, when the aliens attack a port, ship, or island holiday resort. While the aliens and overall atmosphere of X-COM 1 was influenced by popular culture, TFTD has a darker theme influenced by the works of H.P. Lovecraft.

X-COM: TFTD, like the first game, consists of two parts. The GeoScape world view, a 3D map of the world used to track and intercept alien craft, and manage base facilities, research, manufacture, finance, etc. through a series of menus and sub-screens. The BattleScape engine is used for close personal combat between squads of aliens and humans, and takes the form of a turn based, isometric view, in which the player moves and fights with the aliens.