Tau Ceti: Special Edition is an updated, enhanced version of the original game, released for 128K Spectrums in 1987.
The Special Edition contains a number of new features that make playing Tau Ceti easier and more well-rounded.
For starters: the most important addition – in my opinion – is the Library, which contains information on everything from enemy identification charts to files about cities; but its most important addition are the city maps, which make finding target buildings easier. That said: the maps are still quite clunky to use and having to keep referring to them is a bit tedious. Still, it’s better than no city maps, like in the original.
The main game is essentially the same as the original version. There are some enhanced still graphics on some of the screens, but in general the new additions are mostly in the form of extra information. Which is fine because it does make the game better.
More: Tau Ceti on Wikipedia