The original was excellent and had much potential, I would love a sequel, only if they put a large amount of effort and commitment to refining it. I experienced many troublesome glitches in the original that kinda of ruined the original Fracture for me... (one of them won't allow me to continue the campaign now...)
Fracture definitely needs a sequel. Soemthing like another great shooter like Gears of War but with TD on the side. It also needs more vehicles and a better storyline. The storyline feels very rushed in Fracture, and the game is too short to enjoy any real TD. The freeze rifle also needs to do damage instead of just immobilizing. The Lodestone should be upgraded, as well as the Bulldog and Invader. The storyline is too simple and needs more time to develop. SPike grenades should be upgraded and you should be able to carry more grenades. This would help sell many more games than the original.