I've been wondering the same thing. Sadly, I don't really think LDW would care about updating these games to work in offline mode. Such an update would be a really nice surprise, though.

Something I have noticed is that although Virtual Town is an unfinished (and possibly abandoned) game, somehow it appears to still be connected to the LDW servers, since the game needs to access those servers when you first open it on a new day in order to work properly.

I've also been wondering if there is somewhere we can see the leaderboards for such games as Plant Tycoon or the Virtual Villagers series since there's an option to send the player's stats online and receive information about the player's position on the leaderboard.