It's a very old game. One of my first assembly language projects on the Commodore 64...
Score points by running into dots that light up in random locations for a short period of time. Each time you score, tail gets longer. Game ends when you collide with self or walls. After tail gets to a certain length, a new level (reset tail, moves faster). Might be able to dig up a copy of the program, but wouldn't be easy to follow. I wrote my own assembler, no labels, locations and numbers all in hexadecimal, and of course no comments...