Next:
The classic CENTIPEDE (1980/81 Atari).
Classic fixed-screen shooter, but with freedom of movement along the bottom 1/3 of the screen. Rotate the trakball to move a cannon and fire upwards at the titular creature, plus spiders, fleas, scorpions and the mushrooms that litter the playfield. The centipede breaks up into smaller (and faster) pieces when shot, and descends upon the player. It moves back up towards the top of the bottom 1/3 and back down again. A full centipede plunges down quickly at the player if it touches a mushroom a scorpion made contact with ("poisoned" mushroom), and a delay in destroying the last few segments or so causes more to spawn. Holding down the fire button causes rapid fire (though still just one shot at a time) and bonus points are given after a death for each mushroom shot and not destroyed.
I'm thinking I first saw this at Malibu Gran Prix when it was new. The extra life noise (at 10,000 points) is recognizable as one of the most famous arcade sound effects of all time!