Here are some tips for folks wanting to learn how to play Tempest:
1) Flippers flip at a constant rate, so play the angles. You can kill flippers on the outer edge by shooting when they are in the spaces next to you (as they flip). The wider the angle, the more time you have to shoot. You can also move under them as they flip. Good practice is to play level 1 as long as possible without firing. On the open shapes, you will want to hang out on one end of the other (to avoid attacks from both directions). On closed shapes, pick a spot with good angles and good visibility. Often flipping back and forth between two spaces (playing the angles depending on which direction the flippers are attacking from) is all you have to do.
2) Fuseballs ride the lines. The safest place to be is in the space next to one. It looks like it will kill you, but the hit logic only tests the center of the fuseball. Fuseballs will only cross one space at a time before dropping back down (until the end of the round when they start chasing you). If you get stuck with one coming after you at the end of a round (usually on one of the open shapes), try the "Hail Mary" move of spinning very quickly. You can actually jump over one or more spaces (and a fuseball!) if you spin fast enough. Watch out for fuseball tankers at higher levels that split into two fuseballs that will immediately try and jump on you.
3) Pulsars are only dangerous when they are pulsing. Listen to the low, periodic buzz sound. As you get used to it, you will find yourself adapting to this built-in rhythm. You can shoot them when they aren't pulsing or spin out of the way. Watch out for pulsar tankers at higher levels that split into two pulsars on either side of the tanker lane.
4) Regular tankers contain two flippers. Feel free to shoot them and their cargo with impunity. Fuseball tankers are very dangerous. Shoot them and get out of the way. Pulsar tankers are also very dangerous. Shoot them and stay where you are (the pulsars will appear to either side). You can differentiate between the types of tankers by looking closely at their centers. Fuseball and pulsar tankers have tiny pictures of their cargos in their centers. The ability to instantly differentiate between tanker types is probably the most important ability separating good Tempest players from great Tempest players.
5) Spikers are generally harmless (although they do shoot at you), and the spikes they lay down are very handy some times. You can hold the fire button down for continuous fire, but you only get a maximum of eight shots at a time. This is enough to fill half the tube, but not enough for a true continuous stream of shots. If you have a lots of flippers coming after you, find a long spike to sit on top of. You can then hold down the fire button for a machine gun effect. As the spike gets eaten away, look for another one to switch to. Be careful of pulsars and fuseballs when you do this however. When you get to level 65 (black/invisible circle) try riding a full spike all the way down at the end of the round. Your descent rate and rate of fire are perfectly matched so that you can actually blast it away without being impaled all the way to the bottom.
6) Dip Switch #2 (2nd from the back of the game) on the upper bank (at N13) controls demo mode. Demo mode lets you start (and practice) anywhere you like. It does not record scores, however. In normal play, the game will let you start close to where you left off. If you want to "cheat", put the game into demo mode, spin up to where you want to start, start the game and hit the player one start button causing you to zoom down the tube and gain the bonus. Then die and flip the dip switch back to normal mode. Now you can start a real game at the same level and record your score at the end. If you do this often, wiring a front-mounted bypass to that dip switch will come in very handy. There is also a freeze game dip switch that is also handy in case the phone rings while you are playing.
7) Level 81 (green circle) is the highest starting level. Most expert Tempest players agree that green is actually easier than the black/invisible levels that precede it. It is a bit faster, but it restores one of the most valuable visual clues in the game - the tell tale break in the outer edge caused by a pulsar (which is missing in the black/invisible levels). After level 96 (green figure eight/infinity), you are back to the green circle (97) and green square (98). Level 99 is the highest recorded by the game and consists of a never ending supply of random green shapes. Every time you finish the round or loose a life, you will end up with a different shape. To achieve a world record score, you will spend most of your time playing level 99 over and over again. If you can keep your rate of loss to roughly one life per two rounds (at 20K bonus), you can theoretically play forever. Tempest isn't a very good marathon game, however, as it only lets you build up five lives max at any one time. A 30-second bladder break while playing level 99 will pretty much wipe you out. ;-)
8) The highest score recordable by the game is 999,999. Starting at 81, you get there pretty fast (mid way through the greens). With a bit of practice, you can end the game at exactly 999,999. Do that three times and no one will ever be able to beat your score on a single machine (w/o clearing the high score table).
Here are several good Tempest links
GameArchive Tempest Page
Troubleshooting your Tempest Machine
KLOV Tempest Page
Tempest Detailed theory of operation
Tempest Code Project
Mark's Tempest Page