The screen shot above is of an arcade game called Quasar, from Aristotle Software, written for the Apple II by yours truly, Jonathan Dubman. This version is from 1983 and runs inside an emulator on a modern PC.
Directions to download: Click on the following link to download the ZIP file. Most modern Windows installations seem to have WinZip installed; if not you'll need to download that separately.
Extract and the files somewhere (such as the desktop). This yields an icon and a folder. Double-click the icon to launch the emulator. Then click the Apple logo to boot up.
Directions to play the game: This is a variation on the classic "snake" game. You are the orange line, pictured in the screen shot above.
Your mission is to outlast your opponents. All control is with the keyboard -- this game is pre-mouse! The keys to turn are I, J, K and M, which form a diamond (They turn the snake up, left, right, down respectfully.)
Press a key from 1 (slow) to 6 (insanely fast) to start the game from the demo mode. Ctrl-R restarts. ESC pauses and unpauses, and can be used to cheat, sort of.
I'll write more complete instructions later on with options, strategy and additional lore. Unfortunately this 1983 version lacks the bonus rounds and upside down levels that I added by 1985; I still need to track down that newer version.
The freely-redistributable emulator included with this version requires Windows. I'll see if I can get a Mac version working at some point soon to compare Apples to Apples :)