Eggnapper

Eggnapper has a complicated backstory you can see with the in-game instructions by hitting Select at the title screen.

The quick version is, you are in a cave, you have a military fighter with lasers that can destroy most anything you see, including the walls, but not the boss monster "Ralph". You have the ability to carry eggs back to your base, which can then be modified by the base to injure Ralph. Most things you see on screen can kill you, although there are helpful bugs that sometimes eat the things out to get you. If you can take out the 8 balls floating around Ralph's head he will be defeated and you have won the level.