Hay day - Farm with friends and family
OpenTTD - An open-source clone of the classic game ...
FarmVille - FarmVille lets players cultivate their farms by plowing, planting and harvesting crops and trees.
Micropolis - Micropolis is the open source version of SimCity Classic from Maxis, developed by Will Wright and Don Hopkins.
Big Farm - Big Farm is an Awesome, Browser-based, Farming, Single, and Multiplayer Simulation created and published by Good Game.
Simutrans - Simutrans is an open-source transport simulator.