For this achievement, you need to get through the Metro station without using a medkit.
Now the game does not tell you which station is the Metro station (even on the map in the train) unfortunately, but that's what I'm here for right??
The Metro Station is right before the end of Act 1 where you need to reach Ristol. The level itself is pretty straightforward but the beginning part may mess a few people up. The key here is to get off the ladder and run to the right as quickly as you can. I took one hit but that's okay. The rest of the level shouldn't give you too much trouble. If you accidentally press
and use a medkit, you'll have to restart.
Below is a video I made while working on the walkthrough for this game and it should give you a good layout of the map so you know what you're up against.
Sorry, this Game Clip has been removed