I think this game is great. You can play it for hours. Only problem with it is the lack of ending. When you've got all the research done, there's not anything to achieve. I'd like to see different kind of endings (good ending, bad ending.... whatever) or something to do after you have all the basic things at your farm. Maybe upgrading your buildings would work? Or getting wool or milk out of the animals?
Don't get me wrong here. Although I have some points to work on for you, I'm also really wowed by this game. The fact that you made it in 4 days just blows my mind. Great work! I hope to see some other games from you! :) So keep working on!