What toi want to do is go to "settings-keyboard/mouse" and make sure developer console is ON, (be aware this is how I do it for PC). Go back to the main menu and test it out in single player challenge, (it is recommended to use challenge mode instead normal because the game recognizes the cheats and erases the progress. Besides, where's the challenge in that?). After it's booted, press "~" button under the esc button and a code menu will show. Toggle this par pressing it again. Use the code" sv_cheats 1" to turn them ON, (1 and 0 are on and off. Sometimes just using the cheat again turns it...