His people engaged in a war with Earth in 3046, which devastated both sides. He stole a time machine and travelled back to 1966. Using the Lend-a-Hand girls, biotechnology artificially grown from Kustollon genestuff, Igrix wanted to make humanity content so they would not venture into space, thus saving both sides in the future. However, this was done in part by killing scientists whose inventions would accentuate mankind's aggressiveness. Igrix also planned to destroy the Moon so that there was no staging post for humanity to travel deep into space from.
The Ninth Doctor stopped his plan and infected both the Lend-a-Hand girls and Igrix's biotech spaceship with a "human virus", which gave them humanity and independence. This meant that instead of destroying the Moon, the ship decided to explore the universe, with Igrix unable to control it at all. (COMIC: The Love Invasion)