This is the game's most unique feature. Your squad members (Medics, Engineers, and Soldiers) won't follow your orders if they don't trust you.
Prove yourself: Use a Blood Test Kit on yourself to show you aren't an alien. The Thing Inside UsHD
Step 2: Use (Flamethrower, Molotovs, or Flare Gun) to finish them off permanently. This is the game's most unique feature
The film is dialogue-heavy and focuses on the psychological toll of a possible possession or alien presence within the home. The Thing Inside UsHD
You cannot kill "Things" with just bullets.