Congratulations!
To get this achievement, you need to win all 5 victory conditions - technological dominance, country development, victory points, military superiority and overall victory.
Nevertheless, you don't need to win all these in one game.

The victory objectives I have on the screen are victory points, technology and overall victory. The tool tip says completed so that's the bit I'm confused about.

Does that not mean I've won all victory conditions?

引用自 cato：

The victory objectives I have on the screen are victory points, technology and overall victory.

As long as you did not meet the conditions for these victory types, you did not win all victory conditions. The fact that you can see these victory conditions mean that you did not achieve them. Even when you don't see them, it does not mean that you achieved them, it might mean that another player did during the game.

Ah right ok cool. I remember a few messages saying another empire was close to achieving them but I don't remember seeing any reports that someone else had completed them.

Anyway no matter, It's a brilliant game I'm gonna try another game a smaller nation and see how I go.