It occurs to me that making Into the Odd work in the old west basically only requires messing around with the equipment and starter tables. You could argue this is true with almost any setting. However, I've decided to go a step further and create rules for Mexican Standoffs and Duels. I tried to keep them as simple as possible to keep in the spirit of ItO.
Please note, these aren't a replacement for normal combat and shouldn't be used all the time. Standoffs can be a good way to start off a fight, but only when it makes sense. Duels are more involved affairs, and either incredibly deadly or hilariously awkward depending on the skill of the duelists.
Each person involved secretly designates a target. Do this by writing them on an index card or something.
Each combatant then makes a DEX save and records the difference between their roll and their DEX ability score. We'll call this the DRAW. Anyone who fails their DEX save either hesitates or misses their shot.
Starting from the highest DRAW, the player reveals their target and rolls damage as normal. Anyone shot this way forfeits their ability to fire during the standoff, regardless of whether they were rendered unconscious or not.
This continues until everyone has fired or been shot.
Here is an example.
Four gunfighters stand in a circle: Lil Bob, Big Bob, Bobbina, and Dog Horseman. Each of them secretly designates a target, and makes their DEX save.
Lil Bob fails his DEX save right away, so he hesitates. Big Bob rolls a 4 vs a 10 DEX, so his DRAW is 6 (10 minus 4). Bobbina's DRAW is 8, and Dog Horseman's DRAW is 11.
Starting with Dog Horseman who scored the highest DRAW, he reveals his target which is Bobbina. He rolls damage, and Bobbina is shot. Normally, Bobbina would shoot next since she has the 2nd highest DRAW, but she can't because she was shot. Next, Big Bob reveals his target was Lil Bob and rolls damage. Lil Bob is shot, and never got to fire in the first place because he flinched.
From here on, combat would continue as it normally would, favoring the party of the person with the highest DRAW.
Duels use the concept of DRAW but in a different way. In a duel, two slingers face off until some external force compels them to shoot one another.
We do this in rounds. During the first round, both players simultaneously make a DEX save and record their DRAW. We continue doing this until either player fails their DEX save, recording their DRAW each time they roll.
After the first failed DEX save, both players build a dice pool. For each DRAW value that was recorded, find the closest die value that it exceeds, and add it to the pool. For example, if you have a 5, you would add a d4. If you have an 8, you would add a d8. Anything less than 4 is disregarded, and anything higher than 12 is considered a d12.
Both players roll their dice pool, and the highest scorer wins the duel and deals damage equal to the sum of the dice.
Here is an example.
Loose McGoose is facing off against Lucky O'Ducky. In three rounds, they get DRAW values as outlined below.
Loose McGoose: 4, 9, FAIL
Lucky O'Ducky: 2, 8, 7
McGoose's dice pool looks like this: d4, d8.
O'Ducky's looks like this: d8, d6
One die is missing from O'Ducky, because any DRAW lower than 4 disregarded, since there is (for our purposes) no die smaller than d4.
Both roll their dice pools.
McGoose rolls a 7, and O'Ducky rolls a 12. O'Ducky scores fortune's favor and shoots McGoose, dealing 12 damage.
Typically, a duel ends after the first shot, but a less honorable person may choose to continue firing. I leave that up to you.
Q. What happens if both duelists roll the same amount?
A. They both take damage
Q. What happens if neither duelists scores a DRAW higher than 3?
A. They fumble around ineffectually or fire into the air.
Q. What if my character only has 3 DEX?
A. Try shooting people in the back instead.