Cheats > Game > Cheat: 35672

Level select
Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the "config.cfg" file in the game folder. Add the line "sv_iamdone 1" to the file (if it does not already exists). If the line is already present, change the "0" to a "1" to unlock all levels.