ALIEN SYNDROME / Sega / Arcade
Alien Syndrome is Sega's combined take on both Atari's Gauntlet and the movie Aliens. There's six spaceships up there infested with extraterrestrial beasties and filled with crewmembers needing saving, and it's up to you as Guy or Girl (or both simultaneously, if you have a bud handy) to roam to the rescue.
Each level is basically one big deck of a starship, in which there's lots of nasty aliens roaming around and trapped crewmembers in various locations. You've got to find a certain quota of crew before time runs out, then adjourn to the escape hatch at the top of the level. Each one of these little rescue missions concludes with a boss fight against large and odd creatures such as a plant monster who spews Bubbleicious and a purple mutated vagina that can only be shot when the labia parts (watch this review become Google's #1 search result for "mutated vagina" now ... don't let me down Google!).
The game's graphics were actually pretty fab for it's time (1987) and the sound/music are likewise decent, but neither has held up all that well over the course of two decades. The game also just isn't all that much fun. The monsters come at you from every direction and can squirm around pretty fast, but your players are only able to move and fire in eight directions and end up being a little too stiff to contend properly with the continually respawning onslaught. This makes the game come off as a bit clunky and frustrating. The levels are also basically the same thing over and over with little variety.
* Gameplay Video