The Outer Worlds

I started the game with high intelligence so I thought I'd have to do another playthough to unlock this achievement.
Fortunately that was not the case as I was able to lower all my stats using Adrena-Time withdrawal which gives -1 to all attributes. Once I reached the console on the bridge of hope I used about 10 of them a few seconds apart and eventually my intelligence was below average. Then I interacted with the console and I was able to choose the dumb option and skip the Hope myself right into the sun. The dialogue choices are:
1. skip to Terra/Tartarus
2. skip yourself
3. skip into the sun.

Not sure if it matters but this happened on supernova difficulty. You could probably lower your stats more through hunger, thirst and lack of sleep.

Great find from Throni360 - "You CAN do it with +3 intelligence! Just get the Permanent Concussion Flaw. You can get it by stepping on mines and shooting exploding barrels. Repeat it after every cooldown. Switch difficulty to hard if you already have three flaws (maximum on normal)."

Edit: as others have pointed out, you can consume “Adrena-Time“ and suffer from the withdrawal which lowers all attributes by 1. This will allow you to reduce high intelligence down to enable the [Dumb] dialogue option required. Consume one at a time (max stack of 3), wait 15 seconds before consuming the next one, if required. You can see the impact by looking at your character stats.

The following solution was taken from PowerPyx's trophy guide - full credit to PowerPyx.

To earn this achievement you need to from the start of the game during character creation choose to lower your Intelligence stat to below average. This allows you to pick “Dumb” dialogue, which is a requirement for this achievement. Late in the game you will travel back to the Hope, which is the ship your character was awoken from. When you reach the front of the ship you will need to skip it to whichever story destination you’ve been working towards, and can choose to do it yourself or let ADA do it. To earn this achievement you need to specifically pick the [DUMB] dialogue option after saying that you’ll skip it yourself. You will then be shown a cutscene wherein you send the ship straight into the sun, giving you a game over and unlocking the achievement.

- When creating your character at the beginning of the game, if you make his/her intelligence "Below Average" then you will get to use the [Dumb] dialogue options!
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- Deep into the Story you will get the option to "Skip the Hope" yourself or let "ADA" do it... if you have low intelligence you can use the [Dumb] dialogue option to "Skip the Hope into the Sun" Doing this will unlock the achievement
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- To make yourself stupid you can get a FLAW called "Permanent Concussion" (shown in the video) you will be able to use these dialogue options, you can also go to The Un-Reliable to Re-spec your stats if needed
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*3 Flaws is MAX on Normal difficulty so up that if you are going for another flaw to use for this

All of my HD Achievement Guides for The Outer Worlds can be found here! :) (Mobile Friendly)
https://www.bradleafsfan9.com/the-outer-worlds

There is a new and much easier way to do this if you have Very High intelligence, thanks to the Murder on Eridanos DLC. A new item is introduced in the course of the DLC called Spectrum Brown, and it's fairly common (I had 22 of them after completely finishing the DLC). Spectrum Brown has a side effect of Mind Attributes -2 (the status effect is called Brown Vodka Blues and it lasts for 2 minutes). So if your character has +3/Very High intelligence, you can drink a Spectrum Brown and your intelligence will be reduced to +1/Good. You can then use the Adrena-Time trick mentioned in other solutions to reduce your intelligence 2 more points. The [Dumb] option will then show up when talking to Ada on the Hope.

This is much easier than wandering around shooting barrels to try to get the Permanent Concussion flaw (or if, like me, you had already rejected that flaw earlier in the game).

In summary::
1. Get to the Hope Bridge terminal during the main storyline quest Kept Secret But Not Forgotten.
2. Drink Spectrum Brown.
3. Take a puff of Adrena-Time, wait 15 seconds for the crash.
4. Take a second puff of Adrena-Time, wait another 15 seconds for the crash.
5. Your intelligence will now be 5 points lower than it was before. If you started with Very High intelligence, you will now be at Below Average intelligence. You can verify this on the Character - Summary screen in the menu.
6. Interact with the terminal. The dialogue options to choose are Comms--> Patch Ada through --> I'm ready to skip the Hope --> Skip the Hope to Terra 2 --> I'm skipping it myself --> [Dumb] Stand back, ADA. I know numbers real good.

Credit to the above advice, all works well I just added a little step. I was at high so I bumped the play up to hard mode, shot the barrel just outside the door before the terminal (close enough to be hit) and then I took the adrena time every 15ish seconds. Inbetween those shots I added other chems into my inhaler and went to town on my inventory so that all the combined comedowns took me below average. Hopefully that helps a few people.

If you need some help finding Adrena-Times (like i did). I found out that you can get some from the main doctor at the medical bay at groundbreaker. If you aren't able to trade with him then you need to complete any quest (i think) given by Junlei Tennyson located on the right room as you enter the enginnering door at the back of the groundbreaker. If you are able to then trade with the doctor but the adrena-times are restricted then you need to boost your reputation with the groundbreaker by doing some side quests. (Enough Reputation so it is positive, around 65% or higher)

Another way i found you can get adrena-times is by killing Mega Primals on Scylla. I'm not sure if it is guaranteed every kill but from the ones i have killed i have gotten 2 from them.

Another way to get adrena-times is by buying them from Gladys on the groundbreaker. She is located in the rest and go on the left hand side when you enter the main hub. Again if it is restricted then get a positive reputation.

When i got the achievement i had the permanent concussion perk (From getting hit in the head multiple times/blown up by barrels) and i also took around 6 adrena-times. This was enough for me to get the [dumb] dialogue to fly into the sun.

*Also make sure you don't take your adrena-times one after another, i'm not sure if it bugs out but i took one every 15 seconds when it ran out*

Hopefully this helps you, happy hunting :)

The achievement is unlocked when you select the [DUMB] dialog and elect to skip the Hope yourself without ADA’s computational aid—the [Dumb] option is only available if the player-character's intelligence is below average or minimum. The outcome of the action is a bad ending that does not count as a story completion. You will have to reload a save or auto-save created before this decision and request ADA skip the Hope to properly progress the story.

There are ways of decreasing the player-character’s intelligence if your player-character's build incorporated average or higher intelligence. The normal approach is to pop this achievement and, then, reload the most recent save and proceed with the story to unlock:

Adrena-Times syringes provide an effective means of lowering intelligence for this achievement. They are prevalent throughout the game. Each mega-creature will drop several as loot when killed. There are half a dozen mega-creatures in the vicinity of the Fallbrook gate on Monarch if you need to farm them. Additionally, enemies on Gorgon drop them insofar as they are related to the Peril on Gorgon story.

Adrena-Times’ effects (increased movement & melee attack) wear off after 15 seconds. Afterwards, the withdrawal inflicts a -1 penalty to all attributes including intelligence. The withdrawal can be stacked 2 more times for a total of -3 to all attributes including intelligence. You must wait the 15 seconds after each Adrena-Times use for the primary effects to wear off in order to get the withdrawal.

If your character build set intelligence to very high, you will need to adjust it by -4 and stacking Adrena-Times can only get you a max of -3. There are two other ways to reduce intelligence. A concussion provides a -1 penalty to all attributes including intelligence. On supernova, this penalty lasts until the player-character sleeps aboard the Unreliable. If playing on a lesser difficulty, one can get the concussion flaw that will inflict permanent concussion with a -1 penalty to all attributes including intelligence.

The easiest way to get a concussion or the concussion flaw is to allow primals, especially the primal behemoth, to beat up the player-character. Primals can be found in Emerald Vale and on Scylla. Alternatively, if you have left a lot of mines undetonated, you can walk through them to get concussed or use them to get the concussion flaw. If working towards the flaw, it goes without saying, to make a save before you make a go for it either by using primals or mines. Reload the save continuously until you get the flaw.

Spectrum Brown vodka is readily available on Eridanos. If you have not started Murder on Eridanos, you can quickly start it and find a table with half a dozen bottles or so as soon as you enter the hotel. This only takes a few minutes of play. Spectrum Brown provides Mind Attributes -2 that includes intelligence. Drinking more than one bottle increases its 2 minute duration by 2 minutes, with each successive bottle, up to a maximum of 10 minutes. Note that once the effects wear off there is a +1 mind attributes withdrawal effect that creates the opposite result to the one intended.

Once you have below average or minimum intelligence or a strategy to meet the precondition, proceed to the Hope’s main control terminal. (If you want to get the Lost and Found achievement immediately following this one, this is where you should make a manual save if not playing on supernova).

After accessing the terminal, during the dialog, first say, “I’m skipping it myself.” Choose either Terra 2 or Tartarus as the destination, select, “[Dumb] Stand back, ADA. I know numbers real good.” This [Dumb] option is required for the achievement and is only available if the player-character's intelligence is below average or minimum. After some dialog between ADA and the Hope, a cutscene shows the Hope flying into the sun concluding with a “The End” banner. The credits roll and the achievement pops.
The video guide above begins on the Unreliable after the supernova player-character sustains a concussion from a primal behemoth reducing all attributes by -1. This results in his very high intelligence being reduced to high. The guide shows traveling to the Hope and the dialog with ADA upon arriving. It, then, shows a way to stealth through the Hope with no enemy or sentry encounters—gathering an ID cartridge and bridge keycard along the way.

The player-character periodically takes 3 Adrena-Times waiting more than 15 seconds between each dose. This results in -3 to intelligence reducing it to below average and satisfying the prerequisite. Though not necessary, just before the main control console, the player-character imbibes Spectrum Brown Vodka (Mind: -2) further reducing intelligence to minimum. The ensuing dialog shows the player-character’s choice to skip the Hope himself, popping the achievement when the credits roll.

Once you pop this achievement, you can then progress with the game. Load up the save you made at the terminal (or the most recent manual or auto-save if playing on supernova), and proceed with the game. During the dialog at the bridge terminal, allow ADA to skip the Hope. Regardless of how much you may have lowered the player-character's intelligence, ADA will safely skip the ship.

New information, see edit.

If there is a way to do this with Very High Intelligence, w/o the Permanent Concussion flaw, I couldn't find it. Adrena-Time debuffs only stack 3x (you'll need 4 Intelligence debuffs to get to "Below Average" from "Very High") and I couldn't find an explosive crate that gave me a "Concuss" stat close enough to reach the terminal in time (on Normal difficulty).

So if you have a character with Very High Intelligence that did not already obtain the Permanent Concussion flaw, and you've maxed out the flaws on your playthrough (3 for Normal), you'll need a second playthrough, unless you get creative and figure it out, in which case, post a comment.

EDIT:Thanks to the Murder on Eridanos and Peril on Gorgon DLCs, not only is Adrena-Time super plentiful (I must have sold about 500 of them over the course of Peril on Gorgon), but there IS now a way to get this ending with Very High Intelligence.

As other have said, this involves the use of both Adrena-Time and the new item Spectrum Brown. Spectrum Brown's hangover drops your mind attributes by two, and then you can use Adrena-Time's stacking comedowns to get your Intelligence stat low. This precludes the need to stand on mines in hope of getting a Permanent Concussion.

If you need Spectrum Brown for this achievement, I wouldn't say its plentiful on Eridanos, but there are a few guaranteed bottles at Rizzo's Distillation Station, either behind the museum glass or at the taste-test bar. This location is free of enemies until they are triggered by a story mission for the DLC.

Note: The bar at Rizzo's Distillation Station has one of every flavor of Spectrum Vodka. I'm not sure if its the only place you can find some of the flavors, but I highly suggest you don't sell them or throw them away, as they are all needed to unlock the case that holds the Spectrum Gatling science weapon, which is part of the "Spectrum Needler Buddy" achievement.