You can’t stand loosing again. You have to get rid of these players!
But first you need a drink. Walk to the right where the bottles are on a crate. Take the bottle on the right, the whiskey, to take a drink and keep the GLASS. Use the glass on the bottle of whiskey again to get the WHISKEY. Pick up your COAT from the stand on the right and use the coat to take the CIGARETTES out.
Pick up the rifle and you decide that that’s not the best way to kill someone. Leave the tent through the opening on the north. Walk to the right to see the guard. Talk to the guard and learn that he’s bored. He won’t leave his post though. Give the cigarettes to the guard and he’ll take a break.
Walk to the left and open the medical case. Look at the sign on the cover to see how lethal the vials are. Take one of the VIALS. Open the vial in your inventory to pour the POWDER out. Use the empty vial on the heap of SAND on the right of the door to mask your theft.
Use the vial with the vials in the trunk to put it back and no one will notice your switch. Use the yellow powder on the glass of whiskey and nobody will ever know. Ony the whiskey is darker of colour. Enter the tent again and walk to the bottles. Use your glass with the bottle with GIN on the left to make the drink lighter. Walk to the table where the men are playing and give the whiskey to Mr. Hartey.
Game source: A copy of the game was found here on the internet.