Zaxxon

A 1982 Shoot'Em Up created by Sega, Zaxxon was the first Arcade Game to simulate a 3-dimensional view by using Isometric Projection, a form of axonometric projection (hence the name of the game). The game scrolls diagonally through enemy fortresses and outer space as the player's ship dodges the shots of enemy fighters and force field barriers, finally encountering the evil armored robot Zaxxon. Handicaps include the ship's constantly dwindling fuel supply (replenished, as in Scramble, by shooting fuel tanks), and a homing missile that will target the ship if it flies too high. The ship's altitude is indicated on a gauge and by shadows cast on the surface.

Zaxxon received multiple ports to home computers and consoles, though the diagonal-scrolling Isometric Projection was not retained in the Atari 2600 and Intellivision versions. A Mission Pack Sequel, Super Zaxxon, was released for arcades; it replaced the robot boss with a fire-breathing dragon. Sega went on to produce two similar isometric arcade games: Congo Bongo and Future Spy.

Sega later released two console sequels that were considerably different:

Zaxxon 3-D (1987) for the Sega Master System exchanged the isometric view for an into-the-screen view, the better to take advantage of the 3-D glasses packaged with the game.
Zaxxon's Motherbase 2000 (1995) for the Sega 32 X went back to the isometric view, but ships were now rendered in bleeding-edge polygonal graphics.

Tropes used in Zaxxon include:

Antagonist Title: "Zaxxon" is the name of the giant Boss robot.
Attack Its Weak Point: To destroy Zaxxon, you must hit the missile on its left arm six times.
Deadly Walls: Big walls have small gaps to fly through.
Every Ten Thousand Points: You get a bonus fighter at 10,000 points.
Space Is Noisy: Would you believe "space wind"?