Namco made their mark with
space shooters twice before, with
Galaxian in
1979, and
Galaga in
1981. In
1982, however, it was time for
something completely different. Xevious was the first
vertical overhead scrolling space shooter to be released, and more or less
kick-started the entire
Shoot-em-up genre, spawning a million clones, from
1942 to
Vulgus to
Tiger-Heli to
Aleste.
Addendum about the previously noted gameplay: the Xevious themeselves were the alien race that was invading, the Solvalou was your ship, those annoying floating mirrors are called Bacula Resistor Shields, and the proper title for the boss was Andor Genesis Mothership. The game was brought to North America by Atari, and was followed in 1984 by the more difficult "sequel" (although it's better just to call it a "tweaquel") Super Xevious, by a true sequel in 1990 (the 3D game Solvalou), and by another sequel, the lackluster Xevious^3 from 1996. Also, there's a form of side story involving the pilots of the alien tanks in 1984's Grobda.
As far as ports go it was first planned to be brought to the Atari 2600 and Atari 5200, and finally came to the Atari 7800, even though Namco themselves already beat Atari in the home version contest with their near-perfect Famicom/NES port. They followed it up with a pointless Famicom Disk System port of Super Xevious, and then brought it all together with the emulated ports of the original game and Super Xevious on the Playstation's Namco Museum volume 2, plus the Namco Classics-enhanced arrangement version on the PSX version of Xevious^3, known here as Xevious 3D/G. Other noted ports are for the MSX (yep, it was called Xevious - Columbia was a clone), the Apple II, the Amstrad CPC, the x68000, the Commodore 64, the PC Engine, and many others. Microsoft sells it back to Windows9x users in the Revenge of Arcade package, and it's been fully emulated in MAME for quite a while now.
Super Pac Man --- Mappy