THROWBACK TO 1995: Asteroid smashing video game in Microsoft QBasic
Probably won't run in any Windows 7+ command line, but using DOS BOX and QBasic 7.1, can run on either Windows or Mac OS X.
It's a sort of scroller game. Navigate your ship (the one with the red fins) from the left of the screen to the right of the screen without crashing into the asteroids or getting shot by the enemy ships (the ones with the green fins). Then the next level of the game there are more asteroids to navigate through, but only four enemy ships like in the previous level.
Use arrow keys to move your ship, T to shoot torpedoes and P to pause. At least in DOS BOX under Mac OS X, those have to be capital letters, so it might be best to keep Caps Lock on while playing.
I don't remember the scoring scheme other than that you get 500 points for completing a level without crashing or getting shot. I'll have to review the source code to remember the other details.