You need to edit your savegames in order to be invulnerable, you also need a Hex Editor (Hex Workshop). Go into your install dir (default is: C:\Program Files\SEGA\Condemned - Criminal Origins) and click on "view the player data folder". After, go to Save/Profile000/SinglePlayer. Select the savegame on wich you want to be invincible and open it with a Hex Editor (Hex Workshop). Once it open locate this line (not very far from the beginning) DemoModeInvulnerable..0.000000 change it to DemoModeInvulnerable..1.000000 (as you can see you replace the first "0" by "1"). Save the file. Then you can load this savegame and you will be invincible.