Although your Centipede success rests primarily on your ability to observe and react, there are a few strategic techniques that will increase the scores of your games. The major winning tip is: Control the board; don't let it control you. You determine the path of the Centipede. You determine when a Flea will appear and when it won't. There are many tried and proven strategies. Usually, the strategies are so individualistic that it's impossible to translate one person's techniques into winning tips. What is offered here are basic strategic weapons. It's your task to build on them.
Always clear a path through the mushrooms
The path should be at least three mushrooms wide and kept clear at all times. It takes four shots to destroy a mushroom. Count your shots and don't waste them. Whatever you do, don't inadvertently split a Centipede while clearing your path. You'll have too much to contend with. The path will give you a clear shot at the Scorpion at all times. This is essential to your grabbing 1000 points for each Scorpion. Note: For total control of the board, it is best to clear two paths, one on the right and one on the left. This will ensure a clean Scorpion kill before it poisons the mushrooms. Only attempt to clear two paths after you successfully and consistently clear one.
Kill lots of Fleas
Fleas are worth 200 points, and with a little practice, are easily destroyed. Be careful. It takes two shots to kill a Flea. If you only wing it with one shot, it will double its speed to the bottom. The way to attract lots of Fleas is simple: erase all the mushrooms in your working area at the bottom of the screen. The Fleas will keep coming until they have left five mushrooms on the bottom. Make sure you don't split the Centipede by mistake when trying to kill a Flea.
Kill the Centipede in one series of shots
Let the Centipede worm its way down to just above your working area. When you've got a clear shot, strafe it from the head to the tail with a rapid series of shots (your finger pressed down on the trigger). If killed from the head to the tail, you'll get 100 points for each section--for a new head sprouts after you've destroyed the original head. Note: The length of the Centipede diminishes as the screen progresses. The first screen has one 12-segment Centipede (head and 11 segments). The second screen has an 11-segment Centipede (with head) and a single stray head. The third screen has 10 segments and 2 stray heads, and so on. Kill the stray heads as soon as possible. They'll cause you unnecessary trouble if you let them get too close.
Always work on the safe side of the Spider
The safe side is the side to which he isn't heading. If he's going left, stay to the right. The Spider won't be able to attack you (he can't retrace his steps) until he goes off the screen and returns. Don't count on the Spiders for points when you're learning the game. Kill them when practical or necessary. Get your points from the Fleas, the Scorpions, and the Centipedes. Once you're confident of your basic abilities, you can begin to kill the Spider for points. This is dangerous and requires super-sensitive reflexes.
Note: the following strategies were taken directly from the January 1983 Joystik article where Eric Ginner, winner of the 1981 Atari World Championship Centipede Contest, outlined his strategies to the editors.
The Tunnel Strategy
The object of this approach is very simple--create a one-column tunnel through the mushroom field. If the rest of the screen is full of mushrooms, the main Centipede chain will come straight down the tunnel at the beginning of the wave. By firing up the tunnel, every shot will hit a segment of the Centipede chain, and you'll finish it off quickly.
The tunnel should be position under the 1000's digit of the high score so that the Centipede will come straight down it when he appears. The bottom six rows should be kept clear of mushrooms, for good maneuverability while finishing off the Centipede heads. Try to clear the tunnel before each Centipede appears--if there are some mushrooms in the tunnel at the end of the wave, clear them out before the next wave begins.
Since a solid background of mushrooms is necessary for a well-defined tunnel, you should intentionally allow Fleas to drop during the early attack waves. Whenever there is a break in the action, shoot the lowest mushrooms until the Fleas begin falling. Eventually, this will allow the entire screen to fill with mushrooms.
In the Tunnel Strategy, it is best to let Scorpions pass across the screen unmolested. This way the Centipede segments can hit the poisoned Mushrooms, plummet to the bottom and slowly wind back up and down, giving you three opportunities to shoot them before the side feed begins.
The Tunnel Strategy is easy to understand and use, but it is very fast-paced and intense. It requires constant concentration; the only breaks you'll get are at the end of each turn, when it can take quite a while for the poisoned and damaged mushrooms to be tabulated. For very long games (over 500,000 points), the Blob Strategy is slower and safer.
The Blob Strategy
The object of this strategy is to keep enough mushrooms below level 12 to keep Fleas from coming out. A secondary consequence of this approach is that the Centipede takes a very long time to get to the bottom of the screen because there are no mushrooms above row 12 and every segment must cross the entire screen on each of those rows.
On the first wave, you should try to clear the screen of as many mushrooms as possible. After the Centipede has reached row 12 or below, shoot it with a sweeping spray of shots that leaves all of the mushrooms intact.
On the second board, shoot as many of the remaining mushrooms above row 12 as possible by firing around the lower mushroom. Don't risk triggering the Fleas by shooting any of the low mushrooms. (Five or more mushrooms below row 12 will stop the Fleas at this point.) As in the first wave, when the Centipede reaches rows 7-12 you should shoot it and leave it's mushrooms intact.
You should be able to finish setting up the Blob in the third board by selectively removing just the columns that have mushrooms above row 12. Leave the left-most 5 columns open--this will give you a "window" through which to aim at the Centipede. On this and subsequent boards, shoot the Centipede near the top of the screen and remove the resulting mushrooms when the Centipede moves over to the right edge of the screen. It's a good idea to let the last few segments come all of the way down into the Blob area, so you can be constantly adding Mushrooms there.
Note that the Scorpions can leave no poisoned mushrooms in this strategy, because there are no mushrooms above row 12. Also, if you keep your Blob between rows 6 and 12, the Spider cannot eat it because he doesn't rise above row 6 after 180,000 points. This won't last forever, though--at 860,000 points, the Spider will begin jumping all of the way up to row 12, and he will soon eat most of your Blob. So, the Blob Strategy is not effective at scores above 860,000 points.
The Safety Zone Strategy
This strategy was developed in response to the impasse of the increased Spider range at 860,000 points. It makes use of a subtle and important fact: No Fleas fall during the first board of each attack-wave cycle. (An attack-wave cycle is a set of 12 waves, from the full 12-segment Centipede to the 12-heads board.)
By clearing the screen of mushrooms and setting up your safety zone on the last full-Centipede board before 860,000 points, you can simply stay in the safety zone and shoot Spiders until you reach 1,000,000 points, at which point many of the game counters start over.
To set up the safety zone, it is only necessary that there be one mushroom near each edge of row 2. If you keep your shooter in rows 1 and 2, between the two mushrooms, the Centipede can never hit you. This is because the Centipede chain (or heads) will always hit the bottom row outside of the two "outpost" mushrooms, and then travel back up to row 6 without coming between them.
One good way to place a mushroom in row 2 is to shoot the head of a Centipede chain in row 2 and then move to the far side of the resulting mushroom. The chain will drop and reverse, avoiding you completely.
Since it is difficult to get both of the outposts set up on the same Centipede board, it is usually more practical to try to set up just one of them on the first board. If you watch for which direction the Centipede moves when it first comes onto the screen, you'll know which outpost to set up first--only the one on the side opposite from the Centipede's first motion is necessary to keep you safe.
The Safety Zone is challenging, but not particularly exciting. It slows the pace of the game down, and the only excitement comes when a Spider eats one of the outposts, at which point you'll have to think for a short while about how to replace it. But the Safety Zone and its derivative Trap Strategy, are the only reliable way to get through the extended Spider-range boards.
The Trap Strategy
In the Safety Zone Strategy, we saw how proper placement of the mushrooms will divide the bottom 6 rows into two distinct regions; the areas the Centipede can reach, and the areas he can't. In that particular case, however, we were only interested in a quick and reliable method for making that division; the result was that the Centipede was still free to roam the vast majority of the lower screen. By more careful placement of the blocking mushrooms, it's possible to trap the Centipede in a very small part of the screen; the bottom 6 rows of the left-most or right most two columns.
Placing a mushroom in each of rows 2, 4, and 6 of the second column from the edge will trap the Centipede (and all separate heads) in a figure-eight loop there. Then you can just shoot Spiders. If a Spider comes out on the same side as the loop, he will not be able to eat it, because Spiders always jump to the third column from the edge when they appear. In fact, you can get a 900 point Spider every time by waiting at the bottom of the third column. And if a Spider enters from the other side, you have the entire screen width in which to stop him.
It might cost you one or two turns to set up the Trap, but the safety of a well-formed Trap is worth it. Once the Trap is in place, you can concentrate on shooting Spiders. If you set up the Trap on the first wave of an attack wave cycle, no Fleas will fall, and you can clear the screen of all mushrooms except the three that constitute the Trap itself.
Scoring issues and extra men problems
The arcade version has an issue when you reach 996,000 points. The counter that the machine keeps for when to give you the next free man starts immediately at 996K regardless of how many men you have built up. The next free man would be at 1,008,000, but the counter overflows and checks to see if you are over 8,000. After that free man, it will check if you are over 20,000, and so on. It will check once any time points are scored. So, if you hit six things to pass 1M, you're next free man would be at 68K. The score turns over to 0, and the game continues. It can be repeated indefinitely.