PixelJunk Mosters is the most fun I've had with tower defense in, well, ever.
I find the flash games a bit dull by comparision, and far less interactive. By some fluke, I beat Bloons first time, so had little respect for it (four monkeys at the top, then a bunch of those spiky towers crowded in the bottom corner, followed by super monkeys in the middle -- never lost a bloon), and the other games weren't that much better.
And the multi-player on Monsters just rocks. I play it with my daughter all the time.
:)







