Enigma Codes are items you can collect from dead commanders (targets that appear in stealth sections of the game). To unlock Ubercommander assassination missions, you must collect and use them in the Enigma Machine. To quickly get Enigma Codes, select the "Manhattan, Penthouse District" assassination mission at the war map (unlock it if it is not already unlocked). Set the difficulty to the lowest setting under the "Gameplay" option at the options menu. Successfully complete the mission once. Each time you play the mission afterwards, you will find two commanders, allowing you to get two Enigma Codes each time you do this. On the lowest difficulty, you do not have to worry about damage. Drop down and kill the first commander, then drop into the ruined area below and kill the second one. After looting the second commander, open the map and exit it. Ignore the enemies, as you do not need to kill anyone else. Just sprint straight to the commanders, kill them, loot them, and exit. Repeat this as many times as desired to get an unlimited amount of Enigma Codes. This method is also great for maxing out all your perks to reach 100% completion. Lower the difficulty, complete some stealth or combat kills, then exit and repeat. You can raise the difficulty later with no penalty.
Easy weapon upgrades
Once you unlock the "Uberkommandant" mission on Eva's Hammer, select a district on the map and collect the weapon upgrade kit. Then, return to Eva's Hammer to collect it again. You can keep collecting the weapon upgrade from the same mission since it resets each time. Repeat this as many times as desired. Note: This glitch was performed on an unpatched version of the game. It may eventually get patched. To avoid not being able to use this exploit, either do not install new patches before using this exploit or delete the patches. You can avoid patches being installed by disconnecting from the internet until you are ready for the game to install new patches.
Fergus' Arm location
If you chose to save Fergus Reid, you will have to find his arm after a party during the story. To find Fergus' Arm, walk around Eva's Hammer and talk to people until you can narrow the arm's location down to the hangar. Walk up to the top floor and look for two boxes that block the way to a vent. Use your energy weapon to shoot holes into the boxes, then follow the vent until you find Fergus' Arm. Return to Fergus Reid and give him back his arm to complete the quest.
Headshots
Silencing your pistol is a worthwhile upgrade for insta-kill stealth headshots.
Play Wolfstone 3D game
Go to Club Kreissau in the Eva's Hammer hub to play the Wolfstone 3D game. You can access this area whenever you return between missions, and you will get a different level to play on each visit. In the game, you play as a Nazi agent that fights anarchist rebels.
Proper range
Pop a cope on your assault rifle for proper range.
Secret "Riverside" mission
Complete all single Ubercommander assassination missions and collect all Death Cards (except the last one) to unlock the secret "Riverside" mission on the war room map. There is no other map like this in the game. The final area of the mission also has a good view of the Statue Of Liberty ruins.
Stuck on Venus with Constrictor Harness solution
If you chose the Constrictor Harness come to Venus, it is likely that you will get stuck during "Enter The Oberkommando" on the 10th floor. The last part on Venus requires the use of one of the contraptions in the game. Battle Walker and Ram Shackles are very obvious, but if you only have the constrictor harness, it can get a bit confusing because the crouching solution is a bit off. The solution is to just crawl through the narrow spaces, either left or right from the breakable door. This can easily be missed due to the faulty crawling detection in this area. You have look a bit to the side in order to trigger the constrictor harness crawl. If you crouch and look straight ahead, you just walk against the wall.