HI Moonlight!
Welcome to the community as both a consumer and now an author too.
Here is a link for beginners it has lots of fun things from tutorials to guidelines listed.
Master-List Links For Beginners by FairyGodFeather
I know for a fact that there would be a lot of interest in your story, why? CoG did something similar called: Choice of the Rock Star and it is one read all the time.
Now, don’t think just because something similar was done that your story won’t work, because if you put together a first rate story-game all those fans that like the other will be a built in base ready and willing to read and buy your game.
@Fiogan mentioned Tin Star but there is also another western that was done too called Showdown At Willow Creek which means there is room enough for multiple stories in each genre. So, don’t panic, stay calm.
Mom always told me not to do things … writing wasn’t one of them, so according to her rules you should be just fine!
The least that will happen if you go for it is you give it a try and move on… the rewards for trying it and suceeding can include, getting published in both writing and gaming fields, Royalties from a game people buy and lots of other things…
So, ummmm welcome and when you’re ready put up a demo in the WiP sub-forum.