Successfully complete story mode to unlock Magruder's seven barrel Nock gun.
Successfully complete story mode and all side missions (100% completion) to unlock Reed's armored horse and Magruder's Cannon Nock gun. This horse cannot be killed and if ever lost, it will return to the mine.
.69 Ferguson Rifle
Successfully complete the Hunting missions.
Defeat Hoodoo Brown.
Successfully complete the Pony Express missions.
Take a barrel of TNT from the Badlands mine. Find the abandoned house in the Badlands where the buffalo graze. Go to the back of the house on the outside. Face the chimney (looking west) and place the TNT barrel on the left side of the chimney. Blow up the TNT barrel to open a hole in the ground with ammunition for all weapons. The ammunition will reappear over time after you leave the area.
Go to Dodge City. Go to the lower part of the bridge. Follow the path on the other side to reach a beach cave. Look inside for a life power-up which will reappear over time after you leave the area. Note: The cave also contains ammunition and money.
Go to the Indian Hunter's hut, which you can find on your map. Once there, go to the building to the left of the hut, with the stairs going up the side. Go up the first set of stairs, and continue going straight. You should see a spout-type object coming out of the side of the building. Jump onto that spout, and walk toward the wall of the building. If done correctly, you should go through the wall, and into the inside of the house. There is only a small ledge for you to drop onto inside, so move slowly. Once inside, look to your left and you should see three whiskey bottles on the ground. You can pick these up as many times as desired and they will never go away.
For unlimited health, go to Hecht Ranch. Go to the shack next to the windmill. There you will find three whiskey bottles to restore your health.
Sneak up on him and shoot him once. Then, run off and get behind a rock on top of risen ground in the middle of the arena. When he is circling the rock your are behind, you should also circle as well. He will eventually stop and yell at you to come out. He should pace back and forth slowly while you hide behind your rock. When he stops and is not facing you, shoot him in the head. Perform this until the point that he becomes too smart to fall for it again. By then his health should be low enough so that you can run out and keep shooting while strafing. After you have gotten his health down all the way there will be a intermission sequence. Look at your compass at the bottom of the screen. He is the red dot. Find him and he will run at you. Run, but keep firing at him with your pistols and he will blow up.
Never let Reed out of your sight. If he is by himself and you cannot see him, he gains life.
Magruder's Mine mission
At first this mission may seem difficult, but it really is not. In the first part, get your bow ready. Every time Magruder is eater next to or on top of the holes in the ground with the blue green gas coming out of the floor, shoot an arrow into it. When it blows up, it will take some health from Magruder. This will take a few times. To better judge where Magruder is, look on your radar when you are standing by one of the holes on the floor with the blue green gas. When you see a red arrow by you and it is near the hole in the floor, shoot the arrow. When it explodes, run. If you take some hits from Magruder, run for a flask to repent your health. You will most likely run out of arrows, but can find more in the back by the big entranceway opposite of the platform and big pillars that you will need to destroy in the second part of the mission. Keep shooting the arrows at the gas in the floor until Magruder's health bar turns red. After that the second part of the mission begins. To save a lot of your health during the first part, crouch and stay near the outer ring of rocks. If he stands directly in front of you, shoot about one or two arrows at his feet. This will cause him to lose health. If you got hit by his fire, run and find a flask. The second part of the mission is to collapse the cavern on Magruder. Save the game when you get to this part. Do not worry about replenishing your ammunition. Your sniper rifle, regular rifle, and six shooters will suffice. In order to keep one flask and your health to where you do not need to replenish, stay ducked behind the big rocks where you start. Magruder will throw TNT. Use Quick Draw and shoot the TNT. Then, pull out one of your rifles. Use the sights on them. The only way you are going to get Magruder to throw TNT is to hit him in the head. However, it is recommended that you stay and shoot at him from the right hand side of the rocks. That gives you more cover than the left hand side. The trick is how skilled you are at Quick Draw. This is the only way to get past it this part of the mission. Try to hit all the TNT when he throws it. Try hitting the TNT that looks pudgy -- they provide a bigger boom. The small TNT sticks are good, for when hit they will spread out. You can blow the two pillars by Magruder's platform up with them. When he says you are blowing this mine apart, you are half way there. When Cole says there is no one left to help you, the mission is about over. When he throws the three sticks of TNT and you miss and they land by you, run to the opposite side, and then go back to continue. You have two big rocks to blow up to collapse the cavern. The best way to do this is to hit the TNT when it is thrown when they are close to the rocks above Maruder. By doing this you will complete the mission faster. When the second big rock falls, the mission is over and you have completed the game.
Magruder is impossible to kill by shooting, as he is wearing armored plating. Instead, use the bow with exploding arrows. Get Magruder to chase you. As you are backing away from him, shoot an arrow at a geyser as he walks over it. The flammable gas coming from the geyser will explode and damage Magruder until he is almost dead. Then, when he is on the higher level, shoot him in the face with the rifle until he yells then get into quickdraw mode. Get ready to shoot the big package of dynamite when he throws it. After shooting a few sticks of dynamite, the roof will collapse on him.
Easy poker game wins
When you are playing Texas Hold 'em inside the Alhambra, you can easily win with or without a good hand. Raise the bid to the maximum. This should make at least one to three players fold. You can then cheat to make your hand better, and if it is a worse card, forget about the cheat card and go back to your original hand. Afterwards, keep checking your hands until one of you wins. It should be you most of the time. Do not worry if you lose; the tournaments are free.
End of poker cheating
When playing Texas Hold 'em after the tournaments in the Alhambra, you will no longer have the option of cheating.
You can make more money on the bounty hunter side missions by capturing bounties alive. When you find a wanted poster that offers more money if you capture them alive and are having trouble doing so, use the following trick. Kill all gang members or bodyguards (if any). If the bounty is on a horse, kill the horse. Get close and melee attack. This will stun the fugitive and present an opportunity to grab them using LB. Then, press X to subdue the fugitive. This awards you more money for each bounty. If you press LB accidentally and release him, you can try to melee him and grab him again. However, if you do this too many times or if he has been shot, you may kill him and get less money.
Desecrate Hoodoo's corpse
After you defeat Hoodoo, there will be a intermission sequence showing him dead standing up in a coffin. After the sequence, he will still be in west empire standing in the grave. You can take out your double-barrel shotgun and shoot him a few times in some areas. You can shoot off his head, arm, and both of his legs. leaving a corpse floating in an up-right coffin.
Hold Dash while repeatedly jumping your horse to travel about double the speed.
This is a list of all the achievements in Gun, and how to get them:
Across The Badlands Complete (25 points) - Progress through the 'Across The Badlands' level on any difficulty.
Ambush the Train Complete - Progress through the Ambush the Train level on any difficulty.
Attack the Fort Complete (20 points) - Progress through the 'Attack the Fort' level on any difficulty.
Battle at the Steamboat Complete - Progress through the Attack the Fort level on any difficulty.
Bounty Hunter (40 points) - Find and complete all of the Bounty Hunter side missions.
Card Shark (40 points) - Get 100% completion in Poker Tournaments
Defend the Hideout Complete (20 points) - Progress through the 'Defend the Hideout' level on any difficulty.
Easy Difficulty Complete (10 points) - Complete the game on the Easy difficulty.
Escape From Jail Complete (15 points) - Progress through the 'Escape From Jail' level on any difficulty.
Escape the Ambush Complete - Progress through the Escape the Ambush level on any difficulty.
Every upgrade collected - Collect every upgrade in the game.
Every weapon collected - Collect every weapon in the game.
Hard Difficulty Complete - Complete the game on the Hard difficulty.
Hollister's Fort Complete - Progress through the Hollister's Fort level on any difficulty.
Honest Tom Complete - Progress through the Honest Tom level on any difficulty.
Insane Difficulty Complete - Complete the game on the Insane difficulty.
Keeper of the Peace - Find and complete the Keep the Peace side mission.
Law and Order Complete - Progress through the Law and Order level on any difficulty.
Magruder's Mine Complete (70 points) - Progress through the 'Magruder's Mine' level on any difficulty.
Normal Difficulty Complete - Complete the game on the Normal difficulty.
Professional Postman - Find and complete all of the Pony Express side missions.
Professional Prospector - Mine every gold ingot in the West.
Quick Killer Complete - Progress through the Quick Killer level on any difficulty.
Save Soapy Complete (20 points) - Progress through the 'Save Soapy' level on any difficulty.
Stage Coach Complete (20 points) - Progress through the 'Stage Coach' level on any difficulty.
Steamboat Massacre Complete (15 points) - Progress through the 'Steamboat Massacre' level on any difficulty.
Take Down Hoodoo Complete - Progress through the Take Down Hoodoo level on any difficulty.
The Greatest Hunter (40 points) - Find and complete all of the Hunting side missions.
The Hunt Complete - Progress through The Hunt level on any difficulty.
The Red Hand Gang Complete (20 points) - Progress through the 'The Red Hand Gang' level on any difficulty.
The Unrivaled Horseman (40 points) - Find and complete all of the Horse Challenges.
New Game +
Complete the game and return to the starting area (Blackfoot Territory). From the LEFT of the HIGHER boulder leading up to a ledge and gap, jump and spur your horse so it lands on top, then onto the ledge. Cross the next two areas. Stand between the only two rocks in the water. Press and hold LB+LT+RB+RT+A for a few seconds until you hear a strange sound. Go to Options (press [Start]),for a new selection - GUN. Choose any Mission or Cutscene. You will retain ALL weapons, items, and skills.