Cloned Cube is a Portal mod. It takes place after GLaDOS' fall in Portal. You assume the role of Chell's secret clone. You have to escape or else you may just be tested to death. There is one obstacle. CUBiS is trying to kill you.
A change to that old hallway at the end of cc_1 that was full of pipes and stuff. This one now is full of trash and has some new effects like floating dust and stuff like that.