Secrets
There are 2 secret to pick up in the fortress, the first one can be picked up very quickly in theory since you just need to open the external tower on the right and then jump out of the window, before making an aerial dash inside a hole below. Inside is a cheat code, picking it up will activate a teleporter that will send you back up.
The second doesn't appear until a little later, when you change the power source of the fortress using the Crucible. If you step back, you should be able to see the question mark hidden in the ceiling. Look at the stained glass windows high up in the room where the Crucible is located, you should see a large red dot that looks suspicious. Pull on it, it will open a passage to enter the ceiling and pick up a cheat code.
