'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.
A picture from Biplaneworld following the first-pass implementation of an almost 21st century landscape shader.
How many Layers Mit? 4 or 8?
4 atm, with 4 normal maps (which don't *quite* work right yet). A world settings option to choose alternative methods (8 layers, sure) could come later..