One of the puzzles you will need to solve in Amnesia: Rebirth opening the Fortress Gate. The solution is to blast it open. This guide will show you how to exit the Fortress Gate in Amnesia: Rebirth.
To begin with you need to enter the tank at the center of the courtyard so you can find a set of keys. Once you have the keys you need to exit the tank and go left and look for a door that has a short set of stairs leading down to it. You will be able to unlock this door by taking the keys out of your inventory and interacting with them. This will gain you access to the Arsenal where you will now need to scavenge for the ingredients to make the gunpowder that will fill the large tank shell near the workbench with the gunpowder recipe sign. You will be able to find two of the three Gunpowder ingredients in the Arsenal while the third is all the way back in the Quartermaster's Stocks. If you do not have it (8 cups saltpeter) you will have no option but to double back and get it. The required ingredients are:
- 1 cup sulfur powder (located in the Arsenal)
- 1 cup milled charcoal (located in the Arsenal)
- 8 cups saltpeter (located in the Quartermasterâ??s Stocks)
To obtain the ingredients in the Arsenal you need to make your way through the left hallway. There is a tripwire on the floor which you can jump over, in doing so, you will trigger it but the arrow will hit the wall behind you. The first doorway you come across on your right in the hallway is the kitchen and it is here where you will be able to mill your saltpeter and find a pot that will enable you to boil your ingredients. First though you need to find the ingredients.
Continue down the hallway past the dead soldiers until you reach a hanging rug on your left. Walk through it, then pull the wooden window door shut. Now head up the flight of stairs and open the window door you come to so that you come out onto a wooden platform. Carefully walk across it and jump over to the next platform. This will take you to an area with a dead soldier in a chair holding a grenade. Scavenge around to collect supplies and the ingredients to make the gunpowder and then approach the dead soldier. Remove the string attached to the latch, then interact with the string and pull the grenade. Escape the blast by quickly moving to the window you entered from, if you do get hurt and disoriented after the blast use Laudanum to restore your health.
Return to the kitchen you previously passed in the hallway and boil your sulphur in the small pot next to the bigger one on the counter and then at the workbench combine the ingredients you collected into gunpowder. Take out the gunpowder from your inventory and interact with the empty tank shell. Pull the lever to complete the tank shell and then take it to the courtyard.