I love video games. I'm a hobbyist game developer. Having spent years learning and practicing the craft myself, I'm always looking for ways to better understand how and why certain games are or aren't engaging. To that end, I'm going to talk about a game that both frightened and captivated me as a child (though rather than the original, I played the SNES port, which was very good and included a much-needed option to lower the difficulty).
To start with, I'd recommend watching this gameplay video (PHOTOSENSITIVITY WARNING AT 1:35). It's short (<2 minutes) and neatly demonstrates the gameplay loop, which gives a frame of reference for when I discuss the game's atmosphere.
MINIMALISM
Sinistar is not a game with lots of bells and whistles. Largely, this is out of necessity; in 1983, kilobytes and processor cycles were precious, and every one had to be made to count. This has the benefit, though, of making every element in Sinistar well-realized and crucial to the gameplay, and the game itself easy to learn.
You pilot a ship. Your ship has a rapid-firing gun. This gun is multipurpose: in addition to killing enemy ships, it serves as a mining tool, releasing crystals from the asteroids scattered throughout the map. Collect these crystals, and you get "Sinibombs," the only other weapon in your arsenal and the only thing that can harm the game's titular antagonist. You have a radar that shows the positions of nearby ships and asteroids. There are exactly two different kinds of enemy ships: Workers, which also mine the asteroids and steal any crystals you fail to collect in time, using them to build Sinistar; and Warriors, which strafe you with guns that can shoot in 8 directions.
And finally, there's Sinistar himself. He's not there at first, but the Workers are constantly building him. Once he comes alive, he charges at you, chasing you, and you have to survive long enough to pump enough Sinibombs into him to kill him.
INTERESTING DECISIONS
Sid Meier defined a game as "a series of interesting decisions," and Sinistar forces you to constantly make interesting decisions.
Immediately, you want to start mining asteroids. You don't have a second to waste; if you don't have at least 13 Sinibombs by the time Sinistar arrives, you won't be able to kill him, and it will be almost impossible to mine any more with him chasing you. Even if you get 13 Sinibombs, though, you can't relax. You can store up to 20, after all, and Sinibombs can miss - not to mention that every extra you can grab now is one you won't need to mine in the next level.
While you're mining these asteroids, the Workers swarm like flies on rotten meat, ready to scoop up any crystals you don't get to in time, and Warriors constantly swoop in to fire bursts at you. Workers have no weapons and die in a single shot, so you can take them out to stop them from stealing your crystals. Likewise, a single Warrior is easily dealt with if you keep your full attention on it, since they also die in a single hit, your bullets destroy theirs, and you're not limited to firing in 8 directions.
But you can't focus solely on any one thing. You will never have uninterrupted time to mine, and killing Workers or Warriors distracts you from mining, and that is time you can't afford to lose. How long can you shoot this asteroid before you need to clear out some of the enemy ships? How many Workers are you willing to risk turning your own crystals against you? Are you willing to risk dying to a stray bullet from a Warrior? Two Warriors? Five Warriors? The game forces you to constantly juggle these competing priorities.
Finally, there is the matter of Sinistar himself. Your ship's main gun, as mentioned before, does nothing to him. Your Sinibombs home in on him and have very long range, but if there's an intervening enemy or asteroid in the way, the Sinibomb is intercepted and wasted. Your Sinibombs are precious, and you want to save as many as possible for future levels, to say nothing of the risk of not enough hitting this Sinistar to kill him. You want to let Sinistar close in as much as possible to maximize your hit chance, but this is of course inherently risky, since Sinistar is much faster than you are and kills you on contact.
ATMOSPHERE
There were a lot of fun arcade games in the 80s. What brings Sinistar to the level of a classic worth studying over 40 years later is its atmosphere. As I said, I played this game on the SNES, over a decade after it was originally released. I was already accustomed to then-modern, atmospheric titles like Super Metroid, Chrono Trigger, and Doom, and still this game was tense and nerve-wracking to me. I can only imagine what it must have been like to first encounter it in arcade back in 1983.
Sinistar was one of the first games to use digitized voices (the very first being 1980's Stratovox), with the samples themselves having striking clarity compared to its contemporaries like Berzerk. Upon being built, Sinistar announces his presence with a booming "BEWARE, I LIVE." The whole time you are mining asteroids, you will be on edge, dreading those words. The time it takes the Workers to build Sinistar varies. The only way to know how far along they are is to die, with the death screen showing you how much of Sinistar is built - but your lives are precious, and you can't afford to waste them just to satisfy your curiosity. You can never be sure how much time you have, but you know it won't be enough.
Even after you hear that booming voice, though, there's a delay. You won't see Sinistar on the screen yet, may not even have him in radar range, but you know he's coming for you. It's just a matter of time. All the while as he chases you down, he continues to taunt you with lines like "RUN, COWARD" and "I HUNGER." He knows as well as you do how much more powerful he is than you, and he revels in it.
Should Sinistar manage to catch you, he doesn't merely shoot you, or crash into you. No, he eats you, your ship spinning helplessly in front of his mouth while he roars, then crunch, you're dead. Is there any better way of driving home how outmatched you are, how insignificant you are compared to this monster?
CONCLUSION
For a game so early in the industry's history, one made mainly with the goal to take money from children, Sinistar manages to feel like so much more. It's not just an excellent game, it almost functions as a sort of cosmic horror story, putting the player in a position where they face a foe far beyond them and their time is always running out.
Yep.