Stop the violence in Freeside against NCR citizens.
 Quick walkthrough
- Talk the King into ceasing hostilities with the NCR or kill Pacer in such a way that does not implicate the NCR.
 Detailed walkthrough
Once you have completed the quest Things That Go Boom, speak to Ambassador Crocker. He tells you about all the violence in Freeside being caused between the the Kings and the New California Republic personnel stationed there. He gives you two options: kill Pacer, the main person responsible for the violence or solve the problem diplomatically.
 Option: Kill Pacer
If you have already talked to the ghoul Rotface, he may have given you some tips, two of which include the fact that Pacer has a heart problem and too many drugs will kill him and another is he has a feud with the Van Graff family (if you have not talked to Rotface, you open this option by stealing Pacer's treatment records from Julie Farkas' filing cabinet in the Old Mormon Fort). This will add two optional objectives to the quest, one to kill Pacer by adding Psycho to his Jet (requires 60 Medicine) and the other is to kill Pacer in a way that implicates the Van Graff family. You have to do this before his stash appears.
 Method: Frame the Van Graff family (Jean-Baptiste Cutting's note)
- Examine Pacer's stash of jet which is disguised as a carton of cigarettes under his bed, (then try to take it, a prompt will appear stating that you should obtain a note to pin the blame on someone else), then return to Ambassador Crocker.
- Talk to Ralph at Mick and Ralph's and ask him to forge a handwritten note written to Pacer from Jean-Baptiste Cutting. (He will only do this if you have a Speech check of 50 or if the Kings have accepted you.
- Go to Pacer's room (first room on the left, third floor of The King's School of Impersonation).
- Replace Pacer's stash of jet with the handwritten note.
- When Pacer checks his stash, he will immediately run over to the Silver Rush and get himself killed.
This method works even if you killed everyone in the Silver Rush building earlier. Just follow Pacer there after planting the note in his room and kill him yourself with a plasma or laser weapon to frame Van Graffs. It is important to talk to the King before returning to Ambassador Crocker.
 Method: Frame the Van Graff family (working as a guard)
- Start the quest Birds of a Feather.
- While working as a guard, when Pacer comes and talks to you, pick a fight with him by using hostile dialogue options such as the third option in the first dialogue and "Care to back that up?" in the second. This will make him hostile.
- Kill him with the energy weapon the Van Graffs issued you.
Doing this won't make the Kings hostile and will make you successfully complete both King's Gambit (since you killed him with an energy weapon while working for the Van Graffs) and Birds of a Feather (killing him doesn't make you fail this quest). However, killing Pacer will break the quest line G.I. Blues, therefore it is recommended finishing this quest first.
 Method: Frame the Van Graff family (planting energy weapon)
- Wait in or around Pacer's room until night time.
- Sneak into his room and pick his pocket, planting a plasma grenade or mine on him.
- Back up quickly.
Doing this will off Pacer in a way to frame the Van Graffs, so you'll still get the rewards from the ambassador, and the Kings will not suspect you.
 Method: Spike the jet with Psycho (Requires 60 Medicine and 1 Psycho)
To complete this method, either speak to Rotface and give him caps until he tells you about Pacer's addiction or check the filing cabinet in Julie Farkas' wing of the Old Mormon Fort. Then follow these steps:
- Go to Pacer's room (the first room to the left on the third floor of The King's School of Impersonation)
- Add the Psycho to the stash of jet under his bed (roughly between 8A.M. and 9P.M.). The stash is disguised as a carton of cigarettes, but it will only appear AFTER speaking with Rotface or looking through Julie Farkas's files (see above).
- Pacer will die by checking his stash in his room during the night (the earliest time he can be found in his room is about 10 PM).
- Pacer will die immediately when he checks his stash.
 Method: Just kill Pacer
You will fail the quest and lose a substantial amount of fame with Freeside, however you do get a reward (if you apologize) and are still allowed to move onto the next quest. If you wish to easily regain fame with Freeside, go the Atomic Wrangler and talk to James Garret. You will have to pay more caps depending on how infamous you are.
 Option: Solve diplomatically
If you haven't used your favor from G.I. Blues yet, you can use it to ask The King to stop the violence and turn the quest in. However, if you have already used it, the King will say no and you will have to return to Ambassador Crocker and tell him that the King will not stop the violence. Crocker will then give you two options (on top of the option to kill Pacer): Talk to Colonel Moore at the Hoover Dam or talk to Colonel Hsu at Camp McCarran.
 Method: Colonel Moore
- Head to Hoover Dam and talk to Colonel Moore, she will tell you to tell the Kings to stand down or be destroyed and offers to send a squad to back you up.
- Anything you say to the King will cause him to refuse and a fight will break out, and you will fail the mission when you tell Crocker what happened. However you will not gain any Freeside infamy if you let the troopers do all the shooting, and you can get the King's unique suit and you even get a reward of 300 caps from Crocker if you apologize and you get to move onto the next quest. If you do not have Rex as a companion at this time he may be killed by the NCR and you won't be able to recruit him again.
 Method: Colonel Hsu
- Go to Colonel Hsu at Camp McCarran and tell him about the situation in Freeside and he will tell you to offer the King support from the NCR.
- When you get back to the King and tell him the NCR have offered their support. If you are rude to him, his gang will open fire and you will fail the quest, although you will not gain any Freeside infamy if you let the troopers do all the shooting. You can get the King's unique suit and even get a reward of 300 caps from Crocker if you apologize and you get to move onto the next quest.
- If the player is polite, the King agrees to peace with the NCR, but Pacer will attempt an unsuccessful coup of the Kings, and a few Kings Gang Members will start shooting the NCR troopers. Help kill Pacer and the Kings' Rebels and return to Crocker.
 Quest stages
|1||Kill Pacer in a way that implicates someone other than the NCR, or talk the King into ceasing hostilities with the NCR|
|2||Return to Ambassador Crocker with the news that the King has agreed to cease hostilities.|
|3||(Optional) Kill Pacer in a way that implicates the Van Graff family.|
|4||(Optional) Kill Pacer by adding Psycho to his jet.|
|5||Return to Ambassador Crocker with news of Pacer's death.|
|6||Return to Ambassador Crocker with the news that the King will not curb the violence in Freeside.|
|7||Speak with Colonel Moore at the Hoover Dam for further instructions regarding the situation in Freeside.|
|8||Go to the Kings' School of Impersonation and deliver an ultimatum to the King, backed by a squad of NCR troopers.|
|9||(Optional) Speak with Colonel Hsu in Camp McCarran for further instructions regarding the situation in Freeside.|
|10||Go to the Kings' School of Impersonation and offer the King official NCR support if he ceases hostilities.|
|11||Stop Pacer from ruining the deal between the King and the NCR.|
|12||Return to Ambassador Crocker and report that the King has accepted Colonel Hsu's pledge of NCR support.|
|13||Help the NCR Troopers kill all the Kings.|
|14||Return to Ambassador Crocker and report that the Kings have been wiped out.|
- The jet stash under Pacer's bed does not spawn unless the piece of information has been bought from Rotface.
- If you have completed Birds of a Feather the option to imply Pacer's killing by the Van Graffs is already available.
- Choosing the way to kill Pacer will have repercussions on the quest Birds of a Feather
- If you choose to go the diplomatic route and get Colonel Hsu to help resolve the issue, be aware the shooting Pacer and his entourage may cause you to lose considerable fame with Freeside, and/or turn the rest of the Kings against you.
- If the King has died prior to the start of this quest, you can not do the quest. It will not even appear on your Pip-Boy. You must return to the ambassador and tell him the King is dead. He will give you three hundred caps if you apologize, and you will move on to the next quest.
 Behind the scenes
- There are two unused endings to King's Gambit. If the player gets the help of either Colonel Moore or Hsu, then Pacer will object and try to stage a coup. Dialogue was recorded for a further scene where the Player could try to reason with him, and either talk him down with a speech challenge, convince the Kings to shoot him (the only path that can happen on the Hsu route in the finished game), or tell the soldiers to open fire on everyone (essentially what happens on the Moore path). This was presumably cut to make the two different choices more distinct and less redundant. I.e. The player is told Moore will not tolerate any bullshit, so it makes sense that involving her men leads to unavoidable tragedy for the Kings.
- In Chess, a King's Gambit is an opening strategy where a pawn is risked for a long term advantage.
- It was believed that Elvis Presley died of a drug-induced heart attack due to underlying heart problems, much like how Pacer dies if his drug stash is tampered with.
- Ambassador Crocker doesn't continue with the conversation when you give him the update from Freeside after Pacer's death.
If you follow the story line to create a deal, even after Pacer becomes hostile, the King and all the other Kings will become hostile if you shoot or kill him. A fix is to stand still and let the NCR deal with him and the rogue kings.
- prid 001205BC, enable. This should cause the stash of jet to spawn under Pacer's bed. Possible bug fix: Type the following into the console:
- Possible work-arounds: talk to Rotface and look through Julie Farkas's files. This may may cause the jet stash to spawn.
- Ambassador Crocker may not give you a reward when you complete the quest, yet will oddly give you a 300 cap reward when you fail it and apologize.
After accepting the quest you may be approached by an NCR MP who will accuse you of an unidentified crime on the strip and attack you. Re-loading a previous (auto)save just before accepting the quest seems to reset the environment and prevents it from happening a second time, but won't always work. Another choice is to wait outside before going in to talk with Ambassador Crocker, and the NCR MP will come to you, asking for a bribe (200 caps) rather than just attacking on sight. If you are inside, he will not ask for a bribe and will just attack. On PC, this seems not to work.
- Other possible fixes: Just leave the Embassy before the MP approaches you. Outside goes the dialogue in normal way without the accusation and attacking. As an alternative, if the game was saved after taking the quest or you don't have enough time to get out of the building, use a "Stealth Boy" as soon as possible (only works with PC). For Xbox. let the MP come to you and give his speech then turn hostile. Let your companion(s) kill him and he might die without everyone else in the room turning hostile.
- After Pacer turns hostile the game may encounter extreme amounts of lag making it very hard to move. The possible explanation for the lag is because there are so many characters engaging each other in such a small space, that the game engine simply cannot handle it.
When attempting to lace the stash with Psycho, the dialog won't allow it, saying "You could lace it... if only you had some Psycho" despite having numerous Pychos in inventory.
- Possible fix: Though it might be no bug, after discovering the stash (and the King refusing your request) try talking to the ambassador first. With a medicine skill of 60 or higher you can suggest poisoning the jet, which activates the option.
- After talking to Colonel Hsu about NCR help, the option to talk to the King about finishing the quest will be unavailable.
- Birds of a Feather before going back to Crocker to notify him the diplomatic approached failed, access to the NCR Embassy may crash the game. This is a game crippling bug and there does not seem to be any way around it. If you start the quest
- It is possible that if the player does try doing the "King's Gambit" before completing "G.I. Blues" that the quest will be impossible to turn in to the NCR Ambassador after you have completed everything for the quest.
After completing King's Gambit the Courier may be locked out of the strip (you no longer have the key). There are several remedies to this bug:
- Go to Camp McCarran and use the monorail to get to the strip. It is recommend that the player be on good terms with the NCR and have NCR armor. Otherwise, use a Stealth Boy (you may need to leave companions behind if you use a Stealth Boy).
- Take the key from one of the robots. To do this make sure you are [HIDDEN] and snipe the robot from a distance.
- The marker that is pointing to pacers location after the NCR arrive at the King's School of impersonation, pacer may not be standing there at all, even if he hasn't been killed in previous missions, and he will not go check his stash. But if you talk to the king he will talk as if the situation has been dissolved.
- resetquest 0011f95b. After killing Pacer using spiked jet, conversation with Crocker stops. No options in conversation with either Col Moore or Col Hsu to finish quest either. To solve problem enterfollowing reset command using the console: