Well i'd say i would love something like this too.
But from my opinion a plugin or as you can say a mini-game would make the server a bit slower, also it's recommended that a towny server would have little tiny or short time mini-games, as it would make the server a bit complicated, it would make the most idea of the server the plugin you are requesting and not the main server's idea which is survival towny.
(This is just my point of view i don't want anyone to stick to it i just wanted to show it)