At only 500 Wii Points, Defend Your Castle is one of the cheapest WiiWare games yet. Considering it was based on a free online game that can still be played by anyone with a PC or a Mac, we suppose that was a sensible decision.
Initially the game sees you building up points by killing enemies who try to storm your castle. It's enjoyable, if a little easy.
Once you've added all the attachments to your castle you can then spend your points on reinforcing it. It's good fun, but again, a little easy. Finally, you'll get to a stage where your castle's so strong it's almost impossible to lose.