Quickly press A, B, Right, Left, Right, Left, Down, Down, Up(2), Start immediately after the title screen appears.
30,000 bonus points
Destroy the same number of ships as the current level number.
Big Bonus for Challenge Round
In Gyruss, when you reach the challenge rounds in between planets, you're shooting skills are tested against 40 alien ships that fly in various patterns. Normally you try to shoot them all for a whopping 20,000 point bonus, but with this trick you can get 30,000 points with little effort!
During the challenge round, shoot the exact number of aliens as your current round number and let the rest fly away. You'll receive 30,000 bonus points -10,000 more than for all!