Amnesia: Rebirth tries a different tactic than it's brothers in the form of puzzles. Yes, in SOMA and the Dark Descent, there were many puzzles, but it's more complex in Rebirth. Everyone knows trying to complete puzzles is nerve-racking at the best of times, even more so if it's tricky. Attempting to solve it when murderous monsters are hunting you, and you'll come across a new meaning of the word tense! To help you overcome these puzzles so you can't fall into madness, we've got you covered! Here's a guide on how to blow up the fort door in Amnesia: Rebirth.
How to destroy the fort door
We're assuming you've found the radio; if not, check out our guide on how to get to the radio. Upon using the radio, you've learned they are other survivors, huzzah! However, the survivors are not in the fort; they managed to escape and are hidden at a village past the fort. Though to make your way there, a huge door blocks your path!
Head back to the central courtyard and go towards the tank. Yes, you are correct in your thinking, but alas, too early. Open up the hatch, and squirm inside to acquire the key. Now move towards the building to the right of where you entered this area, and go down a flight of stairs, and you'll see a locked door. Open up your inventory and use the key on the door to unlock the Arsenal area.
How to make gunpowder
The main objective here is to create a shell to use in the tank. However, a few ingredients need to be obtained in order to create gunpowder at the gunpowder station.
The first on the list is Saltpeter; if you came from our radio guide, you might have already acquired it. If not, navigate back to the room above the radio room, where you crashed a cannon through the floor. Inside this room is a door leading into a storage area, and upon the wooden shelves is the Saltpeter. This door is closed on your first visit, but the door is open if you return to get the Saltpeter.
The second item is Milled Charcoal. Proceed down the hallway from the gunpowder station, move past the spear trap, and in the room to the right. You will see a lot of charcoal, take a piece and then place it onto the grinding mill on your left. Turn the crank and grind it into dust to get Milled Charcoal.
The third item is Sulfur. At the end of the hallway, you'll see a cage of sorts, where a corpse is dangling through the bars; if you move towards him, in his hand will be a key. Go around the corner, and you'll see a gate. DO NOT OPEN it yet. The gate is rigged to blow. Use the key from your inventory, unlock the gate, and then open the door; the second you do so, run for cover, just be away from the door! Enter the semi-destroyed room and open up the cabinet in the corner of the room; inside is the Sulfur Ointment.
There is another way to access this room by climbing some scaffolding and entering through the window. Doing it this way will save you some sanity, as you can disarm the grenade trap from the inside by taking the hook off the door! But the sanity save isn't as much as you would have thought as you have to make a death-defying jump to get to the window.
Sulfur Ointment is not the same as Sulfur, so we now need to turn one into the other. Go back to the room with the charcoal; on your right-hand side next to the blocked door, there should be a bowl-shaped device, where there's a compartment where you can place a candle inside. Luckily, the candle is always inside, so you need to light it and place the Sulfur Ointment in the bowl at the top. The ointment should start boiling after a while. After it's done, you now have Sulfur.
That's all the items acquired, now head back to the gunpowder station and mix all three together inside of your inventory, and you now have Gunpowder! In the same room, mosey on over to the bullet station and use the newly acquired gunpowder on the empty tank shell and pull down the lever until the shell is sealed.
How to fire the shell
Now head on back to the tank, crawl once again into the hatch. When inside the tank, there should be a wooden handle to your left. Pull down, and this should lower the breach and empty the spent shell. Open your inventory and select your shell and place it into the breach. Pull down the same handle, and it will raise the breach once more. To the left, you'll see a spinny handle; spin it to unlock the turret so it can swivel. Look through the viewport, aim at the door, and fire!