The last two weeks we were looking at something quite different: a text-based adventure system built in Unity. This was inspired by the Henry Stickmin games and also by the old 80s-style choose-your-own-adventure books.
Basic Program Design (Story Card)
The user is presented with a “story card”. A card consists of some text describing their current situation and (normally) a number of options to choose from.
Depending on which option they pick, the story branches from there, card-by-card, until it reaches an end (a card with no options).
Setting up a card is straightforward:
You enter the card description (the text the user sees on screen), the text that the user will see on each option button (the program supports up to four at the moment) and the card (or branch, but we’ll get to that later) to jump to when that option is selected.
There’s also the mention of “States to Set True/False” and we’ll explain that next.
Story States & Story Branches
We could have programmed the system entirely using only cards, but there’s one situation where this becomes tedious. Imagine that you have a choice; hitting a button for example. The consequences of this choice won’t become apparent until later in the story. If we only had story cards, then we’d have to branch the story immediately at his point, replicating the same steps on both branches until the point at which the consequences of your action played out.
Fortunately, there is a better way.
First, to remember the value we introduce the idea of a “story state’. It’s just a container for a true or false value. Cards can set the value of specific states when they are activated as seen above.
So, that covers remembering values, how do we then make use of them? This requires a “story branch”. A branch references a state and two places for the story to go (either of these can be a card or another branch). The value of the state determines which is picked.
This class looks after the story. It is responsible for updating the UI to the details of the current card, for handling the use clicking on specific buttons and generally directing the flow of the story. It also needs a StoryCard to start off the story with.
The project, including a very simple story using a number of cards and also a couple of states, can be found here. There are two scenes in the project, Adventure which contain a simple story and Basic which is a good starting place for your own story.