I'm working on it, almost alone, since december 2012. Some people helped me on graphics, but I'm still searching for a graphic artist to join the studio and work 100% on it.
in the state, the game is already playable alone or in co-op up to 4. You gain levels by playing the 5 firsts maps and can spend skill points on the skill tree to unlock special towers. 17 of the 18 towers are implemented and you can play with them. Each of them has a specific power (fire, water, poison, fear, etc) and a triggered effect (burning, rain, cloud of poison).
The game is still in dev, but I hope you'll like the concept. You can follow the Twitter account of the studio here (Twitter.com) or the FaceBook page of the game with more images and news (Facebook.com). Up to now, I was talking in french, but I will talk both english and french from now.
As the studio has just been created, the game doesn't have a website. But it will come soon.