It’s the second link to Soren Johnson’s blog in a week, but he’s answered a question that people have been asking for while. Alpha Centauri had a unit creation tool, but this feature was not included in Civ 4, even though the latter drew many lessons from the scifi title. Apparently Firaxis thought the tool broke some basic game design rules.

Being able to distinguish units is a key graphical issue (perhaps the key graphical issue) for strategy games, and the Unit Workshop tied the hands of the artists trying to make the game’s sci-fi units look distinct.

And now you know the rest of the story.