You would think a company that's able to program games surely would be able to spell correctly:
"Night Watch Mode: "Enemies will only be targeted if >>their<< viewable."
Whose viewable?
If you like this game-concept you might also want to check out http://www.kongregate.com/games/agame/king-of-drift
also a drift game, but imo a bit better
 "Bubble Tanks Tower Defense 2"){kind=icon}
 "Drift Runners 2"){kind=icon}
 "Shopping Cart Hero"){kind=icon}
 "Epic War 2"){kind=icon}