Andross was a brilliant scientist, and General Pepper had banished him to Venom because of an experiment that the Cornerian Army didn't approve of because it would've ended all disease and hunger. Andross lives in exile until he masses an army to take down the tyrannical Cornerian government and get rid of the evil General Pepper. Star Fox, a team of paid mercenaries, are hired by General Pepper to take down Andross. James McCloud, Peppy Hare, and Pigma Dengar try to destroy the scientist and his work to aid the entire Lylat System, but then Andross is able to fight off James, scare away Peppy, and Pigma realizes that what he did was wrong, and comes to join Andross.
Years pass and a new team of hotshot assassins are hired, led by James's son Fox, with Falco, Slippy, and Peppy by his side. They will do anything for a quick buck. Andross was destined to become the great ruler of Lylat and bring peace, as he has a huge ****ing brain and is extremely wise and has amazing leadership and diplomatic skills, however the new Star Fox team kills thousands of those loyal to Andross on their crusade, where they finally kill Andross and shoot lasers at his brain until he dies.
General Pepper is then seen as a war hero, Star Fox gets their cash, and the government of Corneria maintains it's oppressive rule over it's citizens.