I never liked "Defend your Castle" style games but this one I could not help but enjoy. Bowmaster Prelude has you defending and taking out a base. Your main weapon of choice is, of course a bow. There are different settings you can use to aim; my favorite is an easier setting called point aim where you can just click and the bow will fire.
You don't necessarily have to take out the opposing base in order to win, you just get a lot of points for doing so. The main way to win each level is to take out the enemy waves one by one with your bow and the troops you buy. Each time you kill enemies you get more money to buy powerups and you level up over time to increase your bow power. The powerups are really awesome too. You'll eventually get comet arrows, thunder arrows and a crapload of troops at your disposal.
With all "defend your castle" games this can get pretty addictive. You'll want to get all the powerups to destroy your opponents. What's nice about this game though is that there are different difficulty settings that you can change at any time. So, you can choose to make this a casual game where you take out soldiers and wyverns pretty easy or you an choose to make this game pretty hardcore for a challenge.
Either way, you may hate me for taking away hours of your life to this game.
Click here to play Bowmaster Prelude.