Fortress of Doom: Unlocking Rewards
Certain pieces of equipment such as the Ice Bomb and the Ballista will be given to you at specific moments in history. All you have to do is progress through the campaign to get them. After completing the second mission, a larger part of the fortress will be unlocked, giving you access to more functionality.
As for the many upgrades locked in airlocks, you will need to collect batteries. It takes two of them to open an airlock. You can collect these batteries in the field during missions, and more importantly, you get them by completing the challenges of each mission from the second onwards.
We strongly advise you to unlock them in this order:
- The 2 lower sentinel crystals
- The many Praetor suit points
- Weapon mods
- The armor skins: they are not displayed on the map, there is one in each small outer tower, and one at the bottom and top of the main building.
There are more sentinel batteries available in game than there are slots in which to use them, so you don't have to force yourself to complete every mission challenge.
Unlocking the Unmakyr
It's hard to miss that weapon on display in the middle of the building. You will need to complete the 6 Slayer Gates and collect the 6 Empyrean Keys to open the Energy Cage. The Unmakyr is an alternative to the BFG 9000, which uses the same ammunition. Rather than a high-powered shot, it will release a stream of energy projectiles that will gradually consume your ammunition, allowing you to use it more regularly.
