Unlimited health:-  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.

Unlock:-

Magruder's seven barrel Nock gun:-  Successfully complete story mode to unlock Magruder's seven barrel Nock gun.

.69 Ferguson Rifle:-  Defeat Hollister.

Apache Shirt:-  Successfully complete the Hunting missions..

Dual Peacemakers:-  Defeat Reed.

Silver Spurs:-  Successfully complete the Pony Express missions.

Completion bonuses - 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.

Cavalry Sword  -  Defeat Reed to unlock the Cavalry Sword.

Easy health  -  Go to Dodge City, then 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.

Easy ammunition  -  Take a barrel of TNT from the Badlands mine. Locate 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.

Easy poker game wins  -  When 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 the cheat card is a worse card, just 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, as 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.

Desecrate Hoodoo's corpse  -  After defeating 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 shoot him with your double-barrel shotgun in some areas. You can shoot off his head, arm, and both of his legs, leaving his corpse floating in an up-right coffin.

Defeating Hollister  -  Sneak up on Hollister 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 you are behind, start circling as well. He will eventually stop and yell at you to come out. He should pace back and forth slowly while you hide behind the 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 die.

Defeating Reed  -  Never let Reed out of your sight. If he is by himself and you cannot see him, he will gain health.

Defeating Magruder  -  In the first part of the battle, get your bow ready. Every time Magruder is either 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. You must do this 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 replenish 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 battle. Keep shooting the arrows at the gas in the floor until Magruder's health bar turns red. After that the second part of the battle will begin. 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 battle 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 mode and shoot the TNT. Then, pull out one of your rifles. Use the sights on them. The only way 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 requires some skill at Quick Draw. This is the only way to get past it this part of the battle. 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, as when they are 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 battle is close to 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 battle faster. When the second big rock falls, the battle will be over and you will have completed the game.

Go to Hecht Ranch, then go to the shack next to the windmill. There you will find three whiskey bottles which will reappear over time after you leave the area.

It is not possible to kill Magruder by shooting him, 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.

Gamerscore points  -  Accomplish the indicated task to get Gamerscore points:

Ambush The Train Complete: Successfully complete the Ambush The Train level.
Battle At The Steamboat Complete: Successfully complete the Attack The Fort level.
Escape The Ambush Complete: Successfully complete the Escape The Ambush level.
Every Upgrade Collected: Collect all upgrades.
Every Weapon Collected: Collect all weapons.
Hollister's Fort Complete: Successfully complete the Hollister's Fort level.
Honest Tom Complete: Successfully complete the Honest Tom level.
Insane Difficulty Complete: Successfully complete the game on the Insane difficulty setting.
Keeper Of The Peace: Successfully complete the Keep the Peace Side mission.
Law And Order Complete: Successfully complete the Law And Order level.
Normal Difficulty Complete: Successfully complete the game on the Normal difficulty setting.
Professional Postman: Successfully complete all Pony Express side missions.
Professional Prospector: Mine all gold ingots in the West.
Quick Killer Complete: Successfully complete the Quick Killer level.
Take Down Hoodoo Complete: Successfully complete the Take Down Hoodoo level.
The Hunt Complete: Successfully complete the Hunt level.