I, Fred, am now taking on the central hallway artery of this hideout.
The path seems straightforward, until I'm greeted with a red door blocking the way.
Well, the natural thing to do is to grab a red key card.
As I backtrack towards the entrance, I notice another hallway I overlooked before. Maybe it is obscured by some optical illusion or something.
Trudging through that previously-unnoticed hallway leads to a dead end, with a dais that contains a single red key card – the thing I am looking for.
I grab the card, gulping and expecting something bad…
...which sadly comes true, as several sentry guns appear on the walls of the dead end and pepper me with machine-gun fire of foam darts.
OK, time to skedaddle outta here!
Fortunately enough, those sentry guns don't follow me; and I'm back in front of the red door before I know it.
Just insert this key card here, and… door unlocked.