I love these defence games, they are a lot of fun. You have to build up your defences to save your people from the constant hordes of monsters.
There are many games like this around, but not too many that looks so well or have such an interesting way of presenting the idea.
The indie game was developed by Voodoo Dimention and there is an excellent download available on the games website, linked below. The game has won a good few awards too so give it a go, its quite addictive!