GemCraft
Fun little game I found on Newgrounds.
It's called GemCraft.
Basically there's two points, a hut and a base, enemies exit the base and head towards the hut at a certain pace and along a certain path that's created, you have to set up towers along the path and within the towers you place gems which are your offense against the enemies, you can combine gems which makes the HP they take off greater, you can also throw the gems and let them explode as weapons and lay down water holes to slow the enemy.
Anyway there it was, I spent about 2-3 hours playing it and found it quite entertaining, some may not but yeah.
Enjoy.