Being Watchful

Pay very close attention to your team. If you see someone doing odd things, such as not shooting at enemies when they appear, or moving rather far away from you when your walking, be on alert as this could be a sign of infection. However, do not waste a Blood Test Kit on him to see if you are correct. Just be on alert because they could mutate at any second. This also goes for you as well -- if your team sees you doing the same things, they will question your trust and may attack you.

Unlimited Flares

Highlight "Flare", enable it, but do not throw it down. When it is low, press Left or Right and highlight another object. Then, highlight "Flare" again. It will have restarted and you will not lose another one.

Blood Test Kits

Save Blood Test Kits for showing your team that you are not infected to gain trust. Using them on a team member is useless because they get infected randomly, and usually break out within a minute of infection.

Medi-Packs

Always try to keep medics alive because medical packs can be few and far between. If you want your medic to heal a member of the team, tell your team to stay, then push your medic into the wounded team member. If he is hurt enough, the medic will heal him.

Saving Ammunition

Try not to give all your team members the same weapon because your ammo will go quickly. A good combination is you with a Shotgun or Machine gun, your second man with the one you are not using, then a Pistol. The rest depends on your ammunition supply.

Helicopter Pilot And Whitley

Activate the "Enable game saves" code. When you are in the helicopter fighting the end Boss, press [Esc] and save the game. When you load it, you will not be on the helicopter. Instead, you will be behind all of the snowy mountains and see Whitely and the helicopter pilot models stuck together. At first you will not see yourself. Press [First Person View] once (do not hold it). You will now see your character in third person view. You can separate Whitely and helicopter pilot by shooting them. Unfortunately, you cannot move.

Cheat Mode

Note: This procedure involves editing a registry value; do not attempt this if you are not familiar with working with your system registry, as a mistake can cause serious problems with Windows. Start Regedit and use the "Registry/Export Registry File" menu option to create a backup copy of your original registry. Go to the following entry:

HKEY_LOCAL_MACHINE/Software/Computer 
Artworks/TheThing/1.0 

Create a string value by selecting "Edit/New/String Value" menu option. Name it one of the following "String Value" names and press [Enter]. Right click on the "String Value" name entry that you just created, click "Modify" then type 1 at the "Value Data" field and press [Enter] to activate that code. Note: Replace 1 with a 0 to disable an activated code. Exit and save the modified registry. Note: Cheats will work after a new level is loaded -- loading a saved game will not activate them.

Effect                     Registry String Value  
Unlimited health for player PlayerInvulnerable  
Unlimited health NPCs       NPCInvulnerable  
All weapons                 FullWeaponEquip  

Enable Game Saves

Note: This procedure involves editing a registry value; do not attempt this if you are not familiar with working with your system registry, as a mistake can cause serious problems with Windows. Start Regedit and use the "Registry/Export Registry File" menu option to create a backup copy of your original registry. Go to the following entry:

HKEY_LOCAL_MACHINE/Software/Computer 
Artworks/TheThing/1.0 

Create a string value by selecting "Edit/New/String Value" menu option. Name it DoInGameLoadSave and press [Enter]. Right click on the "DoInGameLoadSave" entry, click "Modify" then type 1 at the "Value Data" field and press [Enter]. Exit and save the modified registry. "Load Game" and "Save Game" selections will now appear in the options menu when you press [Esc] during game play. Note: Do not use "Load Game" option in that menu, as it does not work properly (go back to the main menu instead); however the save option works as expected. The saved game name will be called "TestGameName".