Thexder (NES / Famicom)

It's always interesting to look back at the early days of Squaresoft when Final Fantasy wasn't even a twinkle in its creators' eyes, and the company was making all sorts of different games.  One of these early works was Thexder on the NES.  Players took control of a robot that could transform into a plane, navigating from one level to the next, blowing up whatever stood in their way.  It was simple fun with a bit of exploration tossed in.