Protect the beach from a D-Day-like invasion of penguins in the game When Penguins Attack!!, the game includes beautiful graphics, 6 different maps and 8 unique towers. After you've secured the beaches there are more challenging levels that await you in this quality game. The penguins don't follow a pre-designed path so you can build a maze of towers to make sure the penguins will need to take a lot of time to reach your base.
The Final Borderline is another beautifully designed defense game. The game is present with miniature pixel art which allows you to view a large playing field without having to scroll. Place defensive turrets next to the paths to prevent the enemy creeps from passing, various upgrades are available for each tower.
Mexican Chronicle gives you a whole nother type of defense. In this game one of the most important elements is keeping your soldier's ammo full, every bullet costs money but soldiers without ammo won't have much use.
Scare away birds in Ravens TD, a funny take on the game in a usually so violent genre. Build towers like a rattle or scarecrow to chase away the birds. The game also features objects to place on the path, like a grenade, to be used as a last resort when some birds seem to get through.