Andrew Plotkin’s Quixe Beta: Glulx Games Directly In-Browser!

In a surge of holiday-weekend coding, Andrew Plotkin (Zarf) has progressed his Quixe project to the beta stage and released it for evaluation.  If you’re very familiar with the excellent Parchment project, you’ll know that Parchment provides a Javascript implementation of the Z-machine, which is one of the major virtual machines used in the interactive fiction community.  When you play a game via Parchment, you don’t need plugins or standalone interpreter software at all — you play directly and natively in the browser.  This has obvious advantages for outreach — many people are leery of downloading unknown executable files at all.  And unless your game runs in Flash, convincing someone to install a browser plugin can be almost as hard a sell.  So Parchment has been a great mechanism to make Z-machine games available to not just a wider audience, but to a wide variety of devices as well.  Almost any device that supports a Javascript-enabled web browser can access interactive fiction through Parchment.

But until now, Glulx games were left in the cold.  Glulx is an alternate virtual machine developed by Andrew Plotkin to address some of the limitations of the Z-machine.  There’s more addressable memory as well as support for multiple windows, graphics, and sound, among other improvements.  Inform 7 gives you a choice of using Glulx or one of the Z-machine formats when you compile a game.

Unfortunately, using Inform 7 for a game of any complexity almost forces you into using Glulx, whether you are making use of its enhanced capabilities or not.  Inform 7 generates large game files that easily push past the Z-machine limits.  Particularly if you make use of the growing extension libraries you are likely to inflate yourself right past even the Z8 format’s cap on size.

So Inform 7 developers have (for the most part) found themselves unable to enjoy the same advantages of accessibility and ubiquity that Parchment gives Z-machine authors.

Enter Quixe.  Quixe provides a native Javascript implementation of the Glulx VM.  When combined with a suitable output layer (in this case I believe Zarf is using his own GlkOte implementation) it enables the same type of direct-in-browser play for Glulx-based games that Parchment enables for the Z-machine.

He’s currently got five games up on his page, but authors are able to convert any existing Glulx games using the zcode2js tool, and run them via his engine.  If you do this, you’ll notice that not everything is functional yet.  In particular, if you play the conversion of Rover’s Day Out you’ll miss much of the text formatting and screen effects that are visible in the game when played via a standalone interpreter.  Also, Internet Explorer does not currently work (!) Presumably these problems will be fixed and capabilities will be added in as development proceeds.  I expect we’ll also see the new style model that Zarf has been discussing over the past few months.

And of course, I had to run a conversion of my own Glulx game, Grounded in Space!  Despite not being very long or complex, I had to use Glulx for this game due the need for fairly high-precision floating-point math for one of the puzzles.  I haven’t gone through it in detail yet, but it seems to have converted correctly.  It doesn’t use any odd tricks that should prevent it from being playable, although the geometry puzzle might be even less comprehensible due to style and font issues.  At any rate, it’s very cool to have this capability, and I hope by the time this year’s Comp rolls around we’ll have a much larger number of games able to be played online due to Quixe!

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