The player controls a robot, Unhappy Interface Robot #1984, who lives in a polygonal landscape overseen by Big Brother, an all-seeing eye. In the platforming levels, the player has to run over all of the surfaces to paint them blue (at first; see Palette Swap), while dodging assorted obstacles. Furthermore, if Big Brother's eye is open when the player leaps, he is instantly disintegrated. The platforming stages alternate with short conventional shoot 'em up levels.
Players in a more relaxed mood can also "play" the game in "Doodle City", which lets the player manipulate and draw 3D polygonal objects on the screen.
The game demonstrates the following tropes:
- Advancing Saw Blade of Doom: Some platforming levels end with Robot 1984 entering a doorway. Movement forward through these segments is enforced by a saw blade that cuts away at the level, rendering backtracking impossible.
- A.I. Is a Crapshoot: Inverted. The Unhappy Interface Robot #1984 decides to rebel against Big Brother.
- Border Patrol: Flying saucers in space stages.
- Big Brother Is Watching
- Breaking the Fourth Wall: After completing the set of levels once, a new enemy is added which aims at the camera directly instead of trying to kill the Interface Robot.
- The player is allowed no more than four spare lives at any time.
- The score counter loops around once the score reaches 1 million.
- Every 10,000 Points: You'll get a new life after 20,000 points.
- Everything Trying to Kill You: Including soccer balls, sharks and birds with sunglasses.
- Eye Beams: The Big Brother's eye shoots you if he catches you mid-air.Big Brother: THE LAW NO JUMPING
Unhappy Interface Robot #1984: OH YEAH (jumps around) WHY NOT
Big Brother: (opens eye, zaps the robot) THATS WHY
- Faceless Eye: Who kills you if it catches you mid-air.
- Kaizo Trap: When ending a level's space segment, you can wind up crashing head-first into the walls on the sides of the next level's docking area. Eventually the dock becomes one block in width.
- Non Standard Game Over: Eventually, you can lose all your lives while playing in Doodle City for too long, since it subtracts one life for every minute spent doodling.
- Palette Swap: Level 27 is the same as level 1, except that instead of touching red tiles to turn them blue, you're now touching yellow tiles to turn them green. Plus of course the difficulty is increased, and there's a new enemy (see Breaking the Fourth Wall above or The Fourth Wall Will Not Protect You below). There are 126 levels in totalnote , hence five waves (each with its distinctive palette) altogether (although the last wave is not complete).
- Polygonal Graphics: The Ur-Example (at least when it comes to raster graphics).
- Red Eyes, Take Warning: The eye in levels 53-78, and again in levels 105-126.
- Score Milking: Actively discouraged during the plaforming segments. Beating a level's best time earns an additional bonus, but only for completing it on the first attempt (without dying).
- Score Multiplier: Mostly to encourage players to use the camera control buttons (the two Start buttons) to change the perspective. Zooming in will cause you to score double, while zooming out will cause you to only gain half the points. Then come the Viewer Killers that directly aim at the camera and will kill the player if he/she doesn't move the Robot horizontally or adjust the camera in time."The lower you play, the higher you score."
- Sinister Geometry: Some of the hazards.
- Spelling Bonus: Shooting the letters I, ROBOT (with comma) during the space levels earns an extra life.
- Tech Demo Game: Doodle City seems to exist solely to show off the game's power of drawing many 3D objects on screen.
- Timed Mission:
- The platforming halves of a level; allowing the Bonus Timer to reach 0 will cause the Robot to self-destruct.
- Doodle City also has a time limit which starts at one minute for each life the player has in the main game, and allowing one minute to pass will remove one life form the player's stock. Playing in Doodle City long enough to remove all the player's lives will result in an immediate Game Over, unless you have an credit instead and choose to continue in Doodle City.
- The Fourth Wall Will Not Protect You: After getting through the first loop of levels, you will meet the "Viewer Killers", which aim directly for the player's camera. Moving the Unhappy Interface Robot horizontally or using the Start buttons to change the view angle of the board is the only way they can be avoided.