|Break through four walls|
|Run into a blocked door|
|Some doors have traps behind them|
The contestants are faced with a row of walls - each of which has seven doors in it. Some of the doors will open, but the others won't.
The contestant has to run at a door. If it's unlocked they will burst through and can move on to the next wall. If they choose a wrong door, which is locked, they will bounce straight off and lose.
They have to choose four unlocked doors in a row (one in each of four walls) to make it all the way through.
However, not all the wrong doors are locked. Some will open but have a net fixed behind. If a contestant runs through one of these they'll be caught in the net and also lose the game.
As added hindrances; behind some of the doors are water or mud pits. There's also the Boxing Monster, lurking between the walls, who's there to give the contestants a pummeling!
times; in episodes:
5, 8, 10, 14, 24, 36, 45, 51, 53, 58, 60, 62, 64, 66, 68, 72, 74, 75
Coloured smoke bombs cloud vision of some of the doors.
Guards spray contestants with hoses to distract/hurry them.
|•||Knock Knock was originally built as a starting game for all the contestants to play at once; but viewers requested it to be played as a single-player game. The producers listened and this version of the game premiered in the first episode recorded after the feedback received from the broadcast of the first episodes.|