Lightyear Trophy in Eufloria HD

You only have to defeat all grey enemies. They're on the two large asteroids and on two tiny ones which you can only reach via the large ones. After about 30-40 minutes you should have conquered enough asteroids around the one of the large ones and have got enough seeds, depending on level settings and your recklessness. The final attack takes only a few minutes. Build up an army, swarm the first large asteroid, take the adjacent small one, stock up your army again on your first large asteroid, you should reach the second from there. Don't forget the second small planet and ignore the rest.