Sega Master System / Mark III / Game Gear
Transbot is a version of the classic Defender by Williams. You play on a left to right scrolling backdrop and have to shoot aliens which attack in various inertial patterns. The scenario has you battling through a city to finally reach an underground fortress where THE BIG ONE happens and you get to fight it out with Elgramzon.
There are two gauges that need to be watched, a power gauge which decreases every time you are hit by an alien (you lose a life if it hits zero) and an arm gauge which counts down every time you fire. You can arm your ship from a choice of six weapons by first shooting an arms van that trundles in every so often on the bottom of the screen. If you then catch the pod as it leaves you can choose a weapon from the display. The six weapons are Normal/Beam/Sword/Cannon/Diffuse Beam and Two-way fire.
Graphics are pin-sharp and there are some twisty/turny attack patterns hidden away in the higher levels.