Back in College (around 1997) I use to play this game by Virgin Interactive
called Subspace. It's an overhead multiplayer space game the allows you to run around shooting up other people around the world. The point of the game is to pick up powerups that give you better guns, bombs, faster energy recharge, etc and use your ship to take down others that are trying to do the same. It was dropped by Virgin probably because they didn't see anyone willing to pay for such a simple game. The game while simple to learn, is quite challenging to play against other people. So surprisingly the source was acquired by someone and the servers and a new client are available to play again! The game is now called Subspace Continuum
and let me tell you, its a blast! The system requirements are inline for a computer from 1996, so its not hard to find a computer that can play it. While its not the latest in graphics, and sound it is one of the few free multiplayer games that you can play for a few minutes and not worry about missing out on quests or events.