I have played a bit of Agricola recently. It drives home the appeal of virtual worlds and persistent online games in that it very much is neither. You do not always want that persistence, but Agricola is an economic game that ends potentially open-ended and just as everything is coming together. You set up your farmyard, you upgrade it, you learn an occupation or three, and you’re done — score your farmyard. You want that Civilization “just one more turn” button sometimes. Of course, you are free to extend the rules and do that, or just play freeform, but that’s not really the game.
The single-player version adds a little persistence: keep one occupation per game (and try to beat a higher score), so you become quite the renaissance person although your minor improvements go away.
Or maybe that’s just my having spent too much time with trade skills in-game. There is something satisfying about the stately simplicity of virtual farming, which I suppose explains part of the success of Zynga.
Useful Agricola resource: common mistakes. I am gratified to see that I was making only one, and minor at that.