Scoring

• Destroyed enemies will release one or more coins, which will flit around for a short period before disappearing. Grab these coins with your VacFighter and they will be tallied up at the end of each level, and converted to points. Each coin is worth more as you progress through the levels so collecting coins on later levels can be very lucrative! In general, try to grab every coin you can, but not at the expense of a VacFighter.

• If your VacFighter is destroyed, all the coins that you have collected in that level will be released, so be quick and grab them all again when you reappear. It is considered rude to steal the coins of your fellow player. (But, boy, is it fun!)

• The colour and size of the coin represents its value, with a small silver coin having the smallest worth, and a large gold coin worth oodles!

• Some enemies, most notably ground units, will also release Score Powerups, which will instantly increase your score if you touch them.

• You can have up to 10 VacFighters, including the one in use. You get a free VacFighter at the first 10,000 points, then 30,000 points. After that, each new craft is progressively harder to get, and you'll need another 30,000 points, then another 40,000, and so on.

• To reset the high scores, hold down the Option key and click on the Scores button.

Levels

• The game will remember the highest level that you have fully completed, but only if you start the game from the first level (Mariner Valley). You can select which level you'd like to start from, up to and including this highest level, from the level selection screen. However, be aware that if you start at a higher level, you start with only one VacFighter, the game does not count for high scores and the game will not remember the highest level achieved.

Special Bonuses

• To fully complete the game and qualify for the End of Mission bonus sequence, you must have started from Mariner Valley.

• Destroying all hostile ground targets in a level qualifies you for the 100% Ground Accuracy Bonus. Extra Life bunkers are not included in this count, so don't be too upset if you miss those bunkers as you won't be penalised for it.

• Achieving 100% Ground Accuracy in all levels will qualify you for a massive bonus on completion of the game. It's worth it!

• There are secret ground targets ripe for the bombing in all levels, which can release Shield Powerups, coins and other treasure! No bonuses are hidden in flat, uninteresting areas. (Psst, think Yellowstone! Geysers may be pretty, but they emit noxious, ozone-depleting chemicals. Be environmentally friendly and bomb them!)

• Completing a level without suffering any damage will earn a Shield Bonus. This award increases in value as you progress through the levels. Note that taking damage and recharging via a Shield Powerup will not qualify you for this bonus.

Combat

• Use breaks in the action to power-up your air weapon. Many enemies will cluster together and a well timed weapon release will take out many of your opponents at once.

• If an enemy fires salvos at you, you can often lead its projectiles away from you by feinting in one direction and then pulling back in another.

• Pressing down while the VacFighter is at the bottom of the screen will cause the bomb crosshair to drop down towards the VacFighter. This is good for hitting any pesky ground targets that may slip by you.

• To succeed, you will need to master the art of firing at air enemies and bombing ground targets at the same time. Configure your controls so that you can comfortably hold down the Fire Air Weapon control (for weapon powering-up) while also hammering the Fire Ground Weapon key. If you have to constantly switch between firing at air targets and ground targets, the robodroids will always win.

• Be sure to use the right weapon for the job. For each level that you play, your Plasma Bomb launcher is automatically upgraded for you, but you will need to select which air weapon to use at any given time. The Ion Cannon is a good, basic tool but you'll need to use the other weapons as they become available. Good VacPilots can quickly switch between the different weapons, and know where each is best used.

• Sometimes caution is the name of the game. Many of the ground enemies have certain detection ranges within which they can lock on to your VacFighter. If you are hurting, or simply want to prioritise your targets, you can often hang back and deal with one set of enemies while staying out of range of another.

• If there is a series of peek-a-boo ground targets, they usually don't open up all at once, but in sequence. Try and note the sequence so you can wait in ambush for the first one after they've all fired off their first volley.

• Radars will release random bonuses when destroyed, but they also have another purpose: alerting other forces that you are within range, causing the bad guys to activate. So if you're hurting, you may want to avoid allowing a radar to lock on to you.

• Shenobi Assault Mines aren't as hard as they look. Well, okay, they are, but they're not invincible. Though faster than your VacFighter, they are not quite as agile. Trying to outrun one in any given direction will just land you in a World Of Pain. So don't. Instead, try rapid changes in direction and keep shooting.

• In general, stay loose. Directing the enemy movements and firing sequences by moving your VacFighter around, and timing your attacks, is usually far more lucrative (and easier on your wrists and fingers!) than just blasting away.

Penalties

• The War Crime penalty applies when you bomb a hospital. Sadly, as has often been the case throughout the history of warfare, your opponents have no problems with conducting their operations next to a hospital. So be careful about where you place those bombs!