Impossible Mission: The Voice, the Somersault, the Puzzle

The first thing Impossible Mission does is talk to you. A cackle, and then a voice that sounds like it is being transmitted through a drainpipe full of gravel: another visitor — stay a while, stay forever. In 1984, on a machine whose audio hardware was designed to make three simultaneous tones, that landed somewhere between a magic trick and a threat. People who never owned a Commodore 64 can still do the line.

Which is a shame, in a way, because the voice is the least interesting thing Dennis Caswell did. Underneath the party trick is a game built around an absence, and the absence is the design.

Nobody gave you a gun

Impossible Mission has no attack. There is no weapon, no melee, no charge meter, no consumable that lets you clear a room. Elvin Atombender’s underground complex is full of robots that will kill you on contact, and the complete list of things you can do about them is: run, jump, and somersault.

Consider how unusual that is for 1984. The commercial default for an action game was a shoot button — the arcade had established it, the home ports inherited it, and the interesting design questions were all about what you shot and how fast. Caswell removed the verb entirely and had to replace it with something. What he replaced it with was reading.

Every robot in a room is a moving hazard with a pattern. Some track you, some patrol, some sit on a platform and emit a lethal field on a cycle. Because you cannot delete any of them, your only tool is understanding — where it will be in two seconds, which side of it you can pass, whether the gap between it and the wall is wide enough for a somersault. The room becomes a legibility problem. You stand at the entrance and you look, and looking is the gameplay.

This is the same instinct that makes Paradroid work two years later, though Andrew Braybrooke reached it from the opposite direction — he gave you a way to become the robots rather than a way to avoid them. Both games land on the same conclusion: an enemy you cannot simply delete is an enemy you have to think about, and thinking is more durable than shooting.

The somersault is the whole character

The animation people remember is the flip. Push the joystick and hit fire while running and Caswell’s agent tucks into a somersault, clears a gap, and lands running. It is a big, expensive-looking piece of animation for a 1984 C64 game, and it does something specific that is easy to miss: it makes the character feel like a professional.

Think about what the alternative would have been. A jump. Every game had a jump. A jump is a neutral verb — Mario jumps, and the jump is about the arc and the timing. A somersault is a style statement. It says the person you are controlling has done this before, that the acrobatics are routine, that he is an agent rather than a plumber. Impossible Mission has no cutscenes and almost no text, and the entire characterisation of its protagonist is carried by one animation loop.

That is efficient design, and it is the sort of thing that gets lost when people talk about eighties games as though they were all mechanics with a sticker on top. Caswell had a few kilobytes and a sprite budget, and he spent a disproportionate amount of both on making the running man look competent.

The flip is also a trap. It moves you further than a jump, faster, with a fixed arc you cannot adjust mid-flight. Committing to a somersault in a room you have misread is a decision you get to watch play out for about a second and a half before it kills you. The move that expresses the character’s mastery is the same move that punishes your lack of it.

Thirty-two rooms and a jigsaw

The structure is a search. The complex is a grid of rooms connected by lift shafts and corridors. Each room holds furniture — terminals, sofas, cabinets — and you search each piece by standing on it and waiting, which takes seconds you often do not have because a robot is arriving. The furniture yields puzzle pieces, and the puzzle pieces assemble into nine four-piece puzzles, and the completed puzzles give you the password to Elvin’s control room.

The pieces can be flipped horizontally and vertically, which sounds like an irrelevant detail and is actually the whole difficulty of the jigsaw. Two fragments that look unrelated are the same fragment mirrored. You are also given codes, hidden in the terminals, that reset the lifts or briefly send the robots to sleep — a resource economy layered over the search.

And there is a clock: six hours of in-game time, and every death costs ten minutes of it. That is the design’s cleverest cruelty. Death functions as a withdrawal. You keep your pieces, you keep your progress, and you pay in the one currency the game will not refund. A run of Impossible Mission accumulates damage the way a long night accumulates tiredness, and the failure state creeps up on you across an hour rather than arriving in an instant.

I came to the C64 around the time Impossible Mission was doing the rounds, and I want to be honest about the shape of that: this is a game I know from cassettes that were already second-hand and from the version that had been passed around long enough to have someone else’s handwriting on the label. The 1984 release window is not mine. The game has stayed in circulation ever since, and the argument below is about the design rather than about being there.

The room-by-room problem

The honest criticism is the search itself. Standing on a sofa and holding still while a bar fills is not interesting, and Impossible Mission asks you to do it several hundred times. The tension comes from the robots making it dangerous, which works in a busy room and evaporates in a quiet one. There are rooms in this game where the correct play is to walk to each object, wait, and walk to the next, and the game is doing nothing during that time except counting.

Boulder Dash, released the same year and covered in the grid that taught physics, does not have this problem, because every second of a Boulder Dash cave is the simulation running. Impossible Mission has stretches where the simulation is idling and you are the only thing moving. Caswell’s answer was randomisation — the rooms are generated per game, so the search cannot be memorised — which keeps the game alive across replays and does nothing at all for the minute you are currently living through.

Six hours is an argument

The clock deserves its own paragraph, because six hours of fictional time is a strange number to choose. It is long enough that no single mistake ends you and short enough that a bad half-hour is unrecoverable. Games of the period almost universally used lives — three chances, discrete, memoryless, each one a clean slate. Caswell replaced a countable resource with a continuous one, and the difference in feel is enormous.

Lives make you cautious in bursts. A continuous clock makes you cautious about pace. You start doing arithmetic that no lives-based game ever asks for: this room has four pieces of furniture and three robots, searching it properly will cost me twenty minutes and probably two deaths, is it worth it. That is a resource-management question wearing an action game’s clothes, and it arrived on the C64 the same year the machine was learning what it could do. Roguelikes would rediscover the same tension repeatedly over the next forty years, usually by making the resource food or fuel and calling it attrition.

What it started

The lineage here is longer than the game’s reputation suggests. Every stealth game that gives you no reliable combat option and asks you to read a patrol is downstream of the room Caswell built. Last Ninja 2 inherits the search structure without the elegance. The whole modern habit of building an action game around a verb the designer deliberately withheld — the horror game with no weapon, the immersive sim where violence is the expensive option — traces back through a line that has Impossible Mission close to its head.

It also has one of the best synth-speech performances in games, and I say performance deliberately. The Electronic Speech Systems work is barely intelligible by any modern standard, and the distortion is the character. Elvin sounds like a man who has been living underground with his robots for too long. A cleaner voice would have been a worse one.

Play it on the C64 — the conversions vary wildly, and the original is the one where the speech, the somersault and the six-hour clock all sit at the weights Caswell set them at. Give it an hour before you decide the searching is tedious. Somewhere in the fourth room, you stop looking at the furniture and start looking at the robots, and the game you are actually playing arrives.