Silpheed
Silpheed (シルフィード) is a vertical scrolling shooter developed by Game Arts in 1986. It was ported to various platforms, the last being the Sega MegaCD/Sega CD in 1993.
Concept
Fly the experimental Silpheed fighter to stop Xacalite and his stolen battleship Gloire from destroying the Earth.
Silpheed remains one of the better arguments for owning a Sega CD -- the action is solid, controls reasonably tight, and there are some strategic decisions to be made in the choice of weapon upgrades between stages. The SegaCD version is also one of the few titles that used background full motion video to good effect, with movie elements such as massive asteroids and capitol ship beams providing lethal "no go" areas during critical sections of levels.
Places to Buy
Look for Silpheed on your favorite abandonware or Sega CD ROM site, or (if you're lucky) you might be able to pick it up in a used game shop.