Awesome, best flash game ever.
I only have one critic: when you take control of a place the survivors there disappear.
"thanks for killing the zombies. now we'll take our chances in the infested city."
The game could be more interesting if more choices were added instead of simply switching 2 stones, all with a different energy cost and maybe a cooldown time.
Also, PvP would be awesome
 "Elements"){kind=icon}
 "The Valley Rule"){kind=icon}
 "Escape From 26"){kind=icon}
 "Defender's Quest (lengthy!) Demo"){kind=icon}
 "Rebuild"){kind=icon}
 "Frantic 2"){kind=icon}
 "Angry Aliens: Ecology"){kind=icon}
 "Wings of Genesis"){kind=icon}
 "BioGems"){kind=icon}
 "No Time To Explain"){kind=icon}
 "The Enchanted Cave"){kind=icon}
 "Open Doors 2"){kind=icon}
 "Hero's Arms"){kind=icon}
 "Jumpcat"){kind=icon}
 "Fantasy Kommander"){kind=icon}
 "Smatch"){kind=icon}
 "Bloody Fun Day"){kind=icon}
 "Factory Balls 2"){kind=icon}