Phoenix
The Game: In a heavily armed space fighter, your job is pretty simple – ward off wave after wave of bird-like advance fighters and Phoenix creatures until you get to the mothership, and then try to blow that to smithereens. All of which would be simple if not for the aliens’ unpredictable kamikaze dive-bombing patterns. The 
Phoenix creatures themselves are notoriously difficult to kill, requiring a direct hit in the center to destroy them – otherwise they’ll grow back whatever wings you managed to pick off of them and come back even stronger. (Taito, 1980)
Memories: Phoenix is one of my two favorite games to emerge from the shooting game genre which emerged from the success of Taito’s own Space Invaders. Most shooter games involve chance, luck, and precious little skill, and very few of them give you the chance to try to work out any kind of strategy. Two exceptions I can think of are Midway’s Galaga and this game. [read more]
The Game: Why is it that, when aliens invade the Earth, you’re the only person on call? Doesn’t the front office have a more recent phone list? At any rate, wave after wave of aliens attack, dive-bombing you repeatedly and – providing you don’t blast them out of the sky – rejoining their formations to attack anew. These aliens are a particularly nasty breed, as they can fire while diving and retreating. If you can clear the screen of extraterrestrial nasties, the invasion begins again. Are you getting overtime for all this alien-blasting? What are the benefits like? (Nintendo, 1980)
The Game: It’s quite simple, really. You’re the pilot of a ground-based mobile weapons platform, and there are buttloads of alien meanies headed right for you. Your only defense is a trio of shields and a quick trigger finger. If your cannon is destroyed, its pilot must run for cover; each of the three shields contains an extra cannon. When all three shields are gone, the alien commander – a kind of spaceborne crab – will descend to nearly ground level and hunt the helpless pilot down. Ten rounds of this decide the outcome of the war. (Magnavox, 1980)
The Game: It’s quite simple, really. You’re the pilot of a ground-based mobile weapons platform, and there are buttloads of alien meanies headed right for you. Your only defense is a trio of shields which are degraded by any weapons fire – yours or theirs – and a quick trigger finger. Occasionally a mothership zips across the top of the screen. When the screen is cleared of invaders, another wave – faster and more aggressive – appears. When you’re out of “lives,” or when the aliens manage to land on Earth… it’s all over. (Atari, 1980)
The Game: Another day, another alien invasion. But this time it won’t be so easy to fight the aliens off: your ship has a limited supply of power, and your guns can overheat if you force them to spend too much time blazing away. You have to be judicious with your firepower, dodge incoming fire, and hold out long enough to dock with your own mothership and refuel between waves. (Gremlin/Sega, 1981)
The Game: The evil Gorfian Empire is attacking, and for only a quarter, you can enlist and defend Earth against the vicious (yet strangely cute) little critter with a robotic voice. In the first stage, Astro Battle, you have a defesive shield which is weakened with each shot the aliens fire at you – and every shot you fire back at them. (Truth be told, it’s a very thinly disguised take on the Space Invaders formula.) Then, in the Laser Attack level, the aliens break out heavier, nastier artillery that you have to dodge…if you can. Stage 3 sees a guest star from an earlier Midway game in the Galaxians stage, which is a sort of scaled-down version of the Galaxian game itself. Stage 4 is the hardest, with the Gorfian menace repeatedly spiraling out of a Space Warp, defying you to get so much as a single good shot fired off at it. Finally, if you survive the fourth stage, the Flagship level awaits. The flagship can fire any number of projectiles in your direction through your shield, and you have to not only dodge incoming fire, but try to get your own shot to hit just the right place on the flagship to destroy it. (Bally/Midway, 1981)
The Game: Earth is under attack, but due to defense spending cutbacks (how much planetary defense can you buy for a quarter?), you’re the pilot of the only vessel responding to the emergency. Try to fend off 
The Game: The Martians are coming! And they’re coming in colorful vector graphics! The tripod-like Martian War Machines land, extend their legs, and begin marching inexorably toward your cannon, pausing momentarily to sweep the bottom of the screen with their deadly heat rays, or hurling spirals of energy your way to slow down your cannon. You have a shield that can offer you mere moments of protection, but if it wears out or you find yourself in the Martians’ sights, your spiky-headed cannon operator is fried, and the cannon is promptly manned by another spiky-headed gunner. When your spiky-headed infantry is exhausted, the Martian invasion continues… (Cinematronics, 1981)