Best Left Forgotten Walkthrough (Far Harbor DLC)

In the Far Harbor DLC for Fallout 4, there is a quest called Best Left Forgotten that features some complex and hard-to-solve challenges for players to solve. There are a lot of reasons why this quest is considered challenging, mostly due to the mechanics involved, but players should feel like they can approach this quest with more confidence than before. While this quest threw players for a loop before, they should be able to feel more sure with a little bit of help.

There are many quests in Fallout 4, including some that are hidden, some that are mandatory, and some that will wreck your conscious as you make choices for the survivors of the disaster. However, rebuilding society and bringing survivors with you can make it all worth it, as you form an empire of interconnected settlements pumping supplies to each other along a singular trading route. With this much determination and a little help, you can finish the Best Left Forgotten quest quickly and avoid any frustration with it.

INTO THE NUCLEUS

Finding the Submarine

As you prepare for the quest, you can select it on the Pip-Boy and you will find out that you need to get DiMA’s memories from the Children of Atom, a group with a plot-sized hole in Fallout 4. This is by far the easiest part of the quest as you simply follow the map markers and instructions and go deep into the submarine, The Nucleus. Be sure to pack in some heat or some hacking smarts as there are plenty of robots, computers, and traps waiting to kill cheeky intruders.

Listening to the High Confessor’s speech, convincing him that you are a new member, and telling him have seen the Mother of the Fog will allow you to access DiMA’s memories unimpeded for the majority of the quest. From there you can enter the submarine’s command center, but you will immediately face a fair number of traps including laser tripwires. There are a fair number of robots guarding the area as well, including a Legendary Assaultron, so be cautious of them.

Inside, open the security door and flip the power switch. You will be attacked by another Assaultron after this point. Once power has been restored and Faraday’s program is accessible, players will enter a virtual reality representation of a computer program where they must solve programming error puzzles in order to retrieve DiMA’s memories.

DiMA’S MEMORIES – MEMORY 1

Building Defense Constructs

The setup of this first puzzle simple enough. It’s solved once the players have cleared a path for the little green bugs straight into the yellow data stream​​​​​​, and then they should be able to return to the blue data stream to deposit the memory they obtained. You will solve these puzzles by using the building system in Fallout 4. Make a path for the green bugs by removing one of lighter Code Blocks in the starting area to form a bridge for them.

The next obstacle is the firewall. To deactivate this one, just remove a Code Block that blocks the green Decoder Beam from hitting the firewall. The green bugs will also need another bridge after this obstacle. Just grab one of the Code Blocks and build them one.

Now for the next obstacle, another firewall. All it needs to be deactivated is another green Decoder Beam which is present nearby but is being redirected by a Code Block. Rotate that Code Block so that its green face is pointing at the firewall, redirecting the Decoder Beam.

Once your green indexer bugs have reached the data stream, the program will deploy some sentries to destroy them. Protect the indexer bugs by using the five turrets given by the program and placing them in strategic locations on the map. Once the indexer bugs have successfully transferred the information, simply jump into the formerly yellow data stream which is now blue to continue to Memory 2.

DiMA’S MEMORIES – MEMORY 2

Destroy The Firewall

On to the next memory. Look below and find the Decoder Beam that’s being blocked by a Code Block and remove that blocker. Afterward, follow the Decoder Beam and remove and store any Code Block that’s blocking it. Players will eventually come by a Decoder Relay Block that needs to be rotated to redirect the Decoder Beam to a removable Code Block. Remove that Code Block to make a window for the beam.

This will destroy the first firewall of the puzzle. Soon after that, there is another one. Players will have to stack up some Code Blocks and place a Decoder Relay Block at the top to catch the Decoder Beam and then rotate it to redirect it to the firewall.

Once the big firewall is gone, players will just have to build a bridge for the green indexer bugs to get through to the yellow data stream. As before, once the first green bug touches the data stream, the Sentries will start being hostile to them.

Thankfully, there are turrets here as well and players just have to place them in locations that protect the indexer bugs on their way back to the blue data stream. Once done, jump into the previously yellow data stream that’s now blue for Memory 3.

DiMA’S MEMORIES – MEMORY 3

Building Bridges

For Memory 3, look for the Code Block wall near the starting area and tear it down to build a bridge for the indexer bugs. There will then be an area with two firewalls left and right. Climb the stack of blocks near the firewall on the left side and jump into a small chamber above the firewall. There will be a Decoder Relay Block there and several Code Blocks. Take them all and jump back down.

Once down, build another pillar with the topmost portion being the Decoder Relay Block to catch the Decoder beam and direct it at the left firewall. Once the left firewall is gone, there will new Code Blocks available along with some Decoder Relay Blocks. Grab them all and then move that pillar you made two spaces back so it can hit the static Decoder Relay Block in the wall to dissipate the firewall on the right side.

After that, build a bridge for the green indexer bugs. Once they’re through, the next area will feature a big firewall again. Look to the right side of the firewall and carefully jump at the blocks all the way to the top to reveal the firewall’s weak spot. Build another pillar and place the Decoder Relay Block to redirect the Decoder Beam to the firewall.

Jump down after that and build a bridge for the indexer bugs. After that, it’s the standard reverse tower-defense mode again where the bugs have to be defended while transferring the memories between the data streams. Jump into the blue stream again for Memory 4.

Only three memories are necessary to progress the main quest
but players can go the extra mile and complete Memories 4 & 5 for a bonus reward. The Bonus Reward is the location of
Marine armor
item in
Fallout 4

, which will not spawn if Memory 5 is not complete.

DiMA’S MEMORIES – MEMORY 4

Multiple Firewalls

Memory 4 is more complex than the first three. In the starting area, climb the platform and look for the alcove on the right with the pile of Code Blocks and a Decoder Relay Block. Use those to build a pillar with the Decoder Relay Block at the top to redirect the Decoder Stream to the firewall on the left side. Once that’s gone, grab the additional blocks in the left alcove.

Now on to the bigger firewall. Build two angled pillars that direct the Decoder Beam to the weak spot on the right side of the firewall using the Decoder Relay Blocks to control the Decoder. Note that any block can be attached to any side without the risk of falling off due to gravity.

Make sure to collect all the blocks once the firewalls are gone. Build a bridge for the indexer bugs and then once they’re across, follow the green block line and jump down to see its Decoder Relay Block end. This is the key to removing the final firewall. Look for the Decoder Beam coming from the top and place a Decoder Relay Block to redirect it to the green relay line. This will dissipate the final firewall.

After that, it’s back to the usual turret vs. Sentry game again where the indexer bugs have to be protected. An additional quest dialogue will be unlocked after completing this memory.

DiMA’S MEMORIES – MEMORY 5

Complex Challenge

Finally, you have made it to Memory 5, where the hardest challenge awaits. To see this one in action, check out the above video by YouTuber Oxhorn. Start by grabbing all the available Code Blocks and then building a bridge toward an island with the Decoder Beam pyramid structure on it. Get to the pyramid and grab all the available blocks, including the Decoder Relay Block but take note of where it’s redirecting the Decoder Beam.

Then, build a pillar two blocks high and place the Decoder Relay Block there but this time redirecting the Decoder Beam in the other direction it was originally going. This should dissipate a firewall. Build a bridge to that island with the four pillars, grab all available blocks there, and then build a bridge to another nearby island and grab all the blocks there. Then go back to the island with four pillars and build a vertical pillar that redirects the Decoder Beam to the firewall nearby.

Build a bridge to the unlocked island, grab the Decoder Relay Block, and then build another pillar the redirects the Decoder Beam to the right where there is another island with a beam blocked by a removable Code Block. Once that’s done, make your way back to the center island with the pyramid and build a bridge toward the island where the Decoder Beam is going. Remove all the Code Blocks blocking that Decoder Beam until it’s hitting the green relay wall block.

Then go back to the island with the block pyramid and then back to the Blue Data Stream starting point. Then build a bridge to the left and grab all the blocks you can, then go to the very top of all the static blocks, grabbing any Decoder Relay Block visible. After that, head for where the Decoder Beam is going, remove all the blocks blocking its way, and redirect it toward the nearest firewall weak spot.

Grab the Decoder Relay Block used on the last firewall once that’s done and redirect the Decoder Beam near the Blue Data Stream starting point by building bridges towards the beams and then redirecting the beams with the Decoder Relay Blocks. Once you’ve managed to make the Decoder Beam go between the final firewall and the Blue Data Stream, simply build two-block pillars, top it with a Decoder Relay Block, and then redirect the beam at the firewall. After that, it’s all a matter of protecting the indexing bugs.

This will end the Memory Challenges and unlock the last bit of dialogue and the location of the Marine Armor reward. The stats for the Marine Armor can be seen in the table below:

Completing Best Left Forgotten

Investigating Locations

Once you have finished with the memories, you will have a chat with Valentine and then there are three main locations you must investigate all marked on your map. Follow the map prompts and you will find a nuclear launch code, a kill switch for the wind system, and a secret medical facility. Confronting DiMA about all of these locations and finding answers to your questions in Fallout 4 will officially complete Best Left Forgotten and you will be advanced to the next main quest in.

Video Credit: YouTube|Oxhorn