Undum

Remember those Choose Your Own Adventure, or Fighting Fantasy books? Where you got to choose what your character does next? Well if you think of that in a web-page you have hypertext interactive fiction, or HIF. Instead of turning to a particular page, you click a link, and the next bit of content appears.

To beat the usual limitations, Undum allows you to make the output dynamic. It allows you to keep track of what has happened to the character (any kinds of data, in fact), and to then change the text that gets output accordingly. Effectively it is like writing a CYOA page that is different each time you read it. This allows for far richer and more rewarding game design.

Undum is a pure client client-side library. It consists of a HTML file and three Javascript files. The HTML file uses a nice bit of styling, so there's a bunch of CSS and images in the default package too, but that can be replaced if you want. To create your own game, you edit the HTML file a little (mainly just changing the title and author), and edit one of the Javascript files.

Because the game is written in Javascript, you get the full power of a dynamic and efficient programming language. This isn't a CYOA scripting system with limited functionality. You can take control of anything you want. Or you can just keep things simple using a bunch of simple functions provided by Undum.

Compatibility Undum is designed for HTML5 and CSS3 browsers. It has been tested on Firefox 3.6, Chrome 5, and Safari 5. Older browsers may work okay too, but some of the animation won't work, the styles may render poorly, and saving and loading of games is unlikely to work. Anyone who wants to hack around with it and make it work more widely is welcome. Just fork this project on Github.

Improved Version: Undum’s flexibility and power have made it the engine that drove some of the most significant works in IF (The Play, Almost Goodbye). But it has always been relatively inaccessible. Undum is not the system of choice for writing straightforward hypertext games; it’s a challenging system to learn and use that demands the author build their own engine on top of it to drive their game logic. Consider Raconteur for “Undum with batteries included.” Raconteur

Archived Blog: https://web.archive.org/web/20130127141625if_/http://blog.undum.com/