I designed Vector 3 back in 1979, and am releasing it here for free under a Creative Commons "attribution non-commercial" license. Actually, I've made some fairly substantial changes to the game.
Vector 3 is a 3D space combat board game; its virtue is that players learn the essentials of vector arithmetic and Newtonian mechanics by playing. On a number of occasions, people have told me they learned more about this from the game than from lecture courses. I could see using it in the context of a high-school math or physics course.
It's not a brilliant game, but not a bad one, either. I've rewritten the rules extensively, both to eliminate old-school SPI legalese and make them more readable, and to make some changes that I think improve the game. Mainly, these increase the effectiveness of torpedoes and mines; the problem with games where there's no terrain, facing is unimportant, and there's no equivalent of the weather guage, is that maneuver becomes irrelevant. The presence of missiles and mines at least gives some texture to space, and therefor a reason to maneuver.
As well, the original game was highly constrained by the format in which it was published -- a "minigame" with 100 counters (no more and no less). Though we often playtested with multiple players, it was released as a two-player game, since that's all that the counter limit could accomodate. I've reworked the counters to allow for more -- and of course, in this context, you can always just print more components from your computer.
The zip file linked below contains the full game -- rules PDF, ship display and counters as printable graphics. You'll need to provide graph paper, dice, scrap paper, pencils, and a calculator, however.