The Oregon Trail?? I know how it works, and I’ve wanted to play it for so long but my mother got rid of her old console X–X
Anyway, you could use a random chance at certain points in the game for certain things to happen (ex. drink contaminated water, a small chance you don’t get dysentery)
[You said you aren’t looking for ideas, only how to make certain things, but what do you want to make? If you’re doing what I suggested, here’s a guide on it: Random Chance in Game (Uses Blocks)