Gyruss is a space shoot-em-up game which is a hybrid of Galaga and Tempest. You control a ship at the outer reaches of our solar system, and you must clear all sectors of enemy ships to proceed towards Earth, upon where it all begins again.
Your ship moves around the outside edge of the screen, and you can move around the centre point, shooting and facing inwards. Waves of enemy ships appear on screen from the edge in formations, whilst firing at you, and then move towards the centre where they congregate and you must destroy all ships to move on to the next sector. The ships then break out from the centre singly and swarm and loop out towards you firing at you. Contact with enemy ships or bullets loses a life.
As well as enemy ships to destroy, there are other adversaries to shoot or avoid. On each sector you will encounter a group of three glowing spheres which appear together and can be destroyed for bonus points. The first time they appear shooting the centre one arms your ship with double firepower, and again if you have lost a life and have reverted to single shot power.
Rocks appear which are joined by a tether, and contact with this tether is fatal, so you must shoot one of the rocks to disable the tether. Shooting the rocks awards bonus points. There are also indestructible asteroids which hurtle towards you from the centre of the screen, and these must be avoided.
Upon clearing a sector which takes you to one of the planets, you enter a chance stage. Forty enemy ships appear in various formations and you can shoot these for points. After all forty ships have appeared, and either been destroyed or have left the screen you are awarded a bonus for how many ships have been destroyed, and an extra bonus for destoying all forty.
Extra lives are awarded for 50,000 and 70,000 points.
Shooting a ship: 50, 100 or 150 points.
Destroying a whole formation of enemy ships before the next wave attacks: 1,000, 1,500, 2,000, 2,500 points.
Bonus for clearing a sector (having not destoyed a whole formation): 1,000 points.
Shooting the three glowing spheres: 1,000, 1,500, 2,000 points.
Bonus for shooting each ship on the chance stage: 100 points.
Bonus for shooting all 40 ships on the chance stage: 10,000 points.
Alternative version licensed to Centuri.
Bootleg version called 'Venus'.
Starting lives can be set to 3, 4 or 5. Default is 3.
Difficulty can be set from level 1 (easy) through 5 (average) to 8 (hardest). Default is easy.
Bonus lives can be set to 50,000 and 70,000 or 60,000 and 80,000. Default is 50,000 and 70,000 points.
Learn the formations of the enemy attack waves during the normal stages, to enable you to collect the bonuses for destroying whole waves of attacking ships.
Learn the formations of the enemy attack waves during the chance stages, to enable you to collect the bonuses for destroying whole waves of attackers and the 10,000 for destroying all 40 ships.
The three glowing spheres always appear aligned with where you are located on screen. Remember to avoid any bullets when they appear.
You can fire bullets ahead of enemy ships and then move aside to destroy them and avoid their shots.