I came across this article on Gamezebo's site - End of Cloning by Joel Brodie; it was very interesting regarding the future and cloning of casual games and the best part, it does mention LDW and their games.

To LDW's credit, the reason why their games are not cloned; read this:

"Last Day of Work's real-time strategy games such as Fish Tycoon and Virtual Villagers 1 & 2 are among most popular and best-selling casual games in recent history. Yet, aside from Escape from Paradise (which is more influenced by the look of Virtual Villagers than the actual game play), there are no real Virtual Villagers clones. Why? Not because of lack of demand; rather, it's much more difficult to create a game engine that runs in real-time as Virtual Villagers does than to develop a Mystery Case Files or Diner Dash knock-off."