'A tractor'.. (or 'The Universal', either way)... is an online game for PC. Play games, explore the galaxy, or make your own world with your own game design. Various game types are available - including complex social economies - and you can play it all for free. If you're the creative type you'll find extensive in-game tools and a powerful scripting engine to let you create new game ideas. Or you can just mess around and blow each other into ostriches. It's all cool, whatever.
The playable client allows you to sign up for and participate in the game, but there are no details on the changes in this release.