Yes! you have read that right, you can play Crackdown 2 demo for infinite time thanks to a glitch in the demo. That freezes time at 30 that said, it works in co op game.
Here is how you can do play Crackdown 2 without any time limit.
Start the game.
When you are asked to select the agent, disconnect your console from internet.
Following few prompts, you will be able to start the game with clock frozen at 30minutes.
One thing that you should bear in mind is that, this glitch comes with one bug that is, any rooftops or driving races will cause the game to immediately quit. So, avoid them.
What are you waiting for ? go and have fun.