If you are a fan of Dungeons & Dragons, you will enjoy this. If you’re not, you again, most likely will enjoy this.
https://m.fanfiction.net/s/8096183/1/Ha … Natural-20
This is quite long, and I don’t think this will be finished, but it is still a good read.
What is hard is making code that accepts different and sometimes unexpected types of input and still works.
This is what truly takes a large amount of effort on a developer's part.