Sorry but the game gun dose not have any cheats but i can give you some unlockables and hints.Unlockable:
Reed's armored horse and Macgruder's cannon shotgun
Finish story mode and all side missions for 100% completion. Then go to Macgruder mine to pick up your rewards.Unlockable:
69 Ferguson Rifle
Finish the Hunting Missions.
Beat Hoodoo Brown.
Finish all Pony Express Missions.
Hint: A Hole In The Wall
you take a barrel of TNT from the Badlands mine and put it on the north
end of the old abandoned house's chimney. The explosion will open up a
hole in the ground with unlimited ammunition.
To get there, get out of Dodge City. Make your way to the Badlands
(use your map for directions) and head into the field that has several
horses and buffalo. The house and the mine with the TNT will be right
next to you.
A Hole In The Wall 2
Dodge City go over the lower part of the bridge and follow the path on
the other side to the beach cave. Inside is some ammo, money, and life
pick-up which often respawn when you leave and revisit the area.
you happen to miss a mark when hunting game, you can always depart for
other areas and force the game to respawn the target upon your return.
Try not to miss the next time around.
you scared off the quarry in the Hunt side-missions, just remember
where it was and go to the nearest trader. After you talk to him and
return to where the animal disappeared, it will be there again.
- Enough Talk, Let's Drink. Free Whiskey
to the bridge over at Dodge and go to the bottom by the river. Follow
the river (leftwards) until you come to a little cavern. Inside are
several whiskey bottles that respawn when you recycle the map.