If you're trying to play The Outlast Trials on higher difficulties, you'll need to unlock Reagents. The game doesn't mention how to do that, though, and if you want to do that, this guide will teach you how to unlock Reagents in The Outlast Trials.
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There are a few things you need to do before you can unlock Reagents in the game, and the first is to earn 20 Reagent Tokens. To do that, you need to complete all available trials on the default difficulty and earn the Reagent Tokens.
After collecting 20 of them, you need to go to the main lobby of the game and look for the desk where you can start the Program X trial. This desk is on the opposite side from where you start your normal trials, so you should find the guy easily.
Related: How to Use All Items in The Outlast Trials