The story of Immortal Defense is told through the monologues that introduce each level. At the beginning, these serve as mission briefings, but this function drops off over the course of the game. The story and the gameplay are pretty much separate, as in most games, but few games make a virtue of it the way ID does. If you’re pushing on through the levels regardless of what you’re told is happening in the world, well, the player character is doing the same. Like you, he’s isolated from the in-fiction consequences of his actions. We’re going to be pushing deep into spoiler territory here.
At the beginning of the game, the player character, Subject K, has his mind catapulted into the psychedelic cosmic realm of Pathspace to defeat an imminent alien invasion. The game has six chapters; the invasion by the Bavakh armada is defeated at the end of chapter 1. There’s still no known way to get your mind back into your body at that point, which leaves K isolated from humanity. There’s mention of years passing between levels, time that you’re not aware of. K’s daughter, unborn at the time that he started the mission, grows up and has a daughter of her own. And how do they relate to K? There’s talk of how you’re a hero, a legend. Your alien Pathspace mentor, Pul Wat Aa, is actually worshiped as a god by his people, and it’s not hard to see that down the road. But there’s one thing they never openly acknowledge: they also regard you as a weapon. A weapon that has to be cajoled and manipulated, but still, a highly effective weapon, and one that it would be a waste not to use. And everyone, on multiple sides, wants to use you: for a while, most of the mission briefings seem to be of the form “Why did you do X? Y is more important!” By chapter 5, the granddaughter is asking K to destroy incoming vessels that haven’t been identified yet, just in case they turn out to be hostile. They naturally turn out to be a peaceful scientific expedition by your allies. Even after you learn this, you keep on destroying further expeditions from the same source. The question is raised: why do you keep on doing this?
For the player, the answer is a combination of “because that’s how you advance the plot” and “because there’s nothing else to do”. For K, it’s a bit more complicated, but probably includes the latter. At the end of chapter 2, Aa betrays you and your planet is destroyed, leaving you as a defender with nothing to defend. This begins the revenge-obsessed phase of the game, a phase that lasts for a very long time and involves a number of rash and counterproductive acts on K’s part, as he refuses to let war die down. But what else is there for him to do?
The destruction of your planet also raises a mystery: your body was on that planet. Without it, how is it that you remain in Pathspace? K’s disembodied mind is referred to on multiple occasions as a “ghost”, and that starts to seem literal here. The mystery is in fact quickly solved: a number of your people, including the granddaughter, escaped the destruction, and eventually return to bring new life to the planet through nanotechnology — the same nanotechnology that they’re using to keep themselves alive indefinitely. This gives you something to defend once more, but at the same time, it seems too good, too perfectly wish-fulfilling for K, who regrets never getting a chance to meet his daughter in person. And indeed it all turns out to be a delusion. This is the reason that K destroyed those science fleets: they threatened to discover the truth. But even once this is undeniable, the hallucination of the granddaughter (whose name we’ve never learned) intriguingly argues that the delusions of an immortal are more enduring than mere flesh, and therefore more real. And it’s hard to argue with that from K’s perspective. Everything else around him is going to spend the bulk of eternity dead no matter what he does, including his fellow Pathspace defenders who are still dependent on their physical bodies.
It all reminds me a bit of the second volume of Tezuka’s Phoenix, in which, about halfway through the story, one of the characters is granted immortality. Suddenly the story takes a step back, and all the human conflicts that drove it up to that point fade in importance, as years pass, and millions of years. Something similar happens here, with thousands of years passing between levels, and the old factions and alliances disappearing and being replaced with new things that you’re no longer even given a chance to keep track of. The only thing that remains constant is K’s tenacious and pointless defense of his dead world. By the end, he’s descended into full-bore Jack Torrance insanity, to the point that I have to wonder if the final levels, in which all the boss monsters of the past return in large quantities, are supposed to be “real” at all, or just more hallucinations. (You have to wonder when one of the last ships types introduced is called the “:P”.)
Patrick Dugan wrote of the ending:
“I love you grandpa” is a piece of text that haunted me, leaving me shaken with wonder and existential horror, for hours after I finished the game.
And while I was skeptical on reading that, I have to agree: seen in context, as the last word going into the final mission, it’s devastating. But it isn’t really the last word: at the end of every chapter, there’s a bonus round in a simulation run by Jamesh, the inventor of Pathspace technology, and the final chapter is no exception. Here at the end, his words are a return to rationality, a frank discussion of what you’ve done and his own role in making it possible. And that final step back is the really masterful touch. The author of this game has thought about what it all means, and he wants you to think about it too.
In the official FAQ, the author states:
I put [K's obsession with goals] into gameplay terms by making the last campaign of the story a direct challenge to the player: the missions are getting harder, K is becoming obviously crazier and crazier, and the player understands that there’s no point in world of the game to what he’s doing. The player can “win” in a perfectly acceptable way by just ceasing to play in those final moments: he can set the game aside, never pick it up again, and that means that K has come to his senses and abandoned his efforts.
I have to say this is wrong-headed. From a player’s perspective, abandoning a pre-scripted story in mid-game doesn’t change what happens in the gameworld any more than stopping reading a novel before the ending changes what happens in the world it describes. Even losing a mission, which in theory could allow the Bavakh invasion to succeed, doesn’t seem like something that happens in the “real” story of the game. There are games where the sense of what really happens is flexible, but this isn’t one of them. But as the same FAQ says, “I’m still on the fence about this–which is why you can also achieve a certain kind of victory by finishing.”
Apparently there’s a seventh chapter, set in “Hellspace”, that only becomes available if you complete every mission with a 100% survival rate. I imagine I’ll try for that eventually, but I’ll be surprised if it adds anything significant to the story. Pleasantly surprised, but surprised.