I wound up with an great team for the 2011 Global Game Jam; you can enjoy fruits of our labors here. For now I'll just repost the description I wrote there, lest this post blossom into a constant string of terrible puns.
The game is a hotseat 2-player game with three factions: The organic apple farmer, the genetically modified apple farmer and the viral blackberries. It's designed so that play the game entirely by clicking on map tiles to perform context-sensitive actions.
-Each tile has numbers showing the rounds left until the lease expires (on the left) and the crop yields a profit (on the right). When the lease is down to 0, you’ll get the option to renew it.
-An apple crop on a tile with Fertility 10 makes 100% of the maximum profit ($20). On a tile with Fertility 5, the profit would be 50% of the maximum ($10).
-It costs $8 to lease a tile for 10 turns, $5 to clear plants from a tile you own, and $5 to plant a crop. Organic crops take 5 rounds to yield a profit; GMO crops only need 4.
-On the other hand, GMO crops deplete the soil twice as quickly. They also can’t be planted next to any non-GMO plant, not even diagonally. Better plan accordingly...
-Beware blackberries! They’re a bigger problem for the GMO farmer (since he can’t plant crops next to them), but if you let them grow out of control both sides will regret it.
-Harvesting a crop depletes that tile’s Fertility. Rain improves the Fertility of any empty tile by 1. Blackberries only grow after rainfall. . .at first.
-If an Organic crop is immediately downwind of a GMO crop, cross-pollination occurs; the Organic crop is replaced with a fresh GMO crop, under the Organic player’s control.
-Cross-pollination never happens diagonally. GMO crops behave the same no matter who owns them, so an Organic farmer might want to clear his GMO crop before it infects its neighbors.