Tau Ceti is a science fiction themed computer game first published in 1985 by CRL for the ZX Spectrum and later converted to several other platforms. It was designed and programmed by Pete Cooke. It was groundbreaking at the time for its extensive use of 3D graphics, shadow effects and its large gameworld set on a small planet, Tau Ceti III, orbiting the titular star. The planet also has a realistic day and night cycle (much shorter than our own).
An enhanced version (known as Tau Ceti - The Special Edition) was released for the 128K Spectrum and Amstrad CPC in 1987 featuring extra graphics and a large amount of accessible library data about the gameworld and the game.
A sequel, Academy, was released in 1986.
Source: Wikipedia, "Tau Ceti (video game)," available under the CC-BY-SA License.