The only requirement is having finished the game, even if it was on the easiest difficulty ('Can I Play, Daddy?').



This means you can select the final chapter, "Chapter 16: Return to Deathshead's Compound", from the chapter selection screen.

Select "Chapter 16: Return to Deathshead's Compound" from the chapter selection screen and then select Über difficulty. When the game starts, open the console by pressing Ctrl + ~ on your keyboard. For me, the ~ key was the key below the Esc key (although that one is labeled ² and ³ for me whereas the ~ symbol is found elsewhere on my keyboard, so it may depend).

When you've succesfully found the ~ key and pressed it together with the Ctrl key, the console will open. Enter the following command and press Enter.


If you entered it correctly, a yellow and red text reading "WARNING: Archived CVar 'g_permaGodMode' in production mode" will appear.

Next, enter the following command and press Enter.


If you entered it correctly, a yellow and red text reading "WARNING: Archived CVar 'g_permaInfiniteAmmo' in production mode" will appear.



Press Ctrl + ~ on your keyboard to close the console. You are now immortal and will have infinite ammo. So just breeze your way through the level and the boss fight but STOP WHEN DEATHSHEAD GOES DOWN AND YOU'RE PROMPTED TO PRESS A KEY/BUTTON TO FINISH HIM.



Since achievements don't unlock when you're 'in cheat mode', you first need to disable both cheats again. So open the console and enter the following command (same line but -1 instead of 1) and press Enter.


Note: you can scroll back through commands you entered earlier by means of the Up Arrow key. So you can recall the command you entered earlier and just add the minus to the command line before pressing Enter.

If you entered it correctly, the same yellow and red text reading "WARNING: Archived CVar 'g_permaGodMode' in production mode" will appear. If another message appears, something along the lines of "can't be 2", that means you forgot to add the minus before the 1.

Next, enter the following command and press Enter.


If you entered it correctly, the same yellow and red text reading "WARNING: Archived CVar 'g_permaInfiniteAmmo' in production mode" will appear.



Now, feel free to finish Deathshead, enjoy the end scene of the game and more importantly, enjoy seeing those last two achievements unlock for you.

If cheating weighs heavily on your gamer's conscience and you just want to cheat through the very final part of the chapter instead of the entire chapter, just start "Chapter 16: Return to Deathshead's Compound" from the chapter selection screen and then select Über difficulty.

Play through the chapter until right before the second part of the final boss fight. Go get the two Assault Rifles from the weapons stash and equip them with rockets.



Now enter the two cheat codes through the console (see previous section). When Deathshead goes down and you're supposed to press the action key to finish him, first disable both cheats (see previous section) and only then finish off Deathshead.

Cheating is fun until someone gets hurt, so use the console responsibly.



Also note that cheats will remain on until you switch them off, even after starting a different chapter and maybe even after restarting the game. So don't forget to disable cheats if you want to experience the game as intended again, and if you want to be able to unlock some more achievements.