IFComp authors create their games using any tools they wish to use. As a result, the games during a given comp year will involve a wide variety of file formats. This short guide gives you, the IFComp player, a quick rundown of the most common formats and how to play them.
Most of these game formats will work on any modern computer, but some require additional software to run. You can identify the “flavor” of an IFComp game (and know what else you need to play it) by its main file’s extension, as described below.
You can find a list of interpreters on IFWiki for all file formats described below.
File extensions: .gblorb, .zblorb, .ulx, .z5, .z8
There are two ways to play these games, which are created using the Inform IF authoring tool:
Download an appropriate interpreter for your operating system, and have it load the game file that (since you’re reading this) you’ve already downloaded.
Play the game on the ifcomp.org website by locating its entry in the game list and clicking its “Play Online” button or link.
Note that games in this format are usually parser-based IF, in the mode of Infocom’s classic text adventures. To play them, you type in commands like GET LAMP and KILL TROLL WITH SWORD and ASK ZOE ABOUT QUANTUM PHYSICS and so on. Playing these games as intended requires knowledge of (and comfort with) parser conventions.
Some games contain some basic instructions if you e.g. type HELP as your first command. You can also find links to parser primers and tutorial games on the ifcomp.org website.
File extension: .html
Nowadays the most common single format for IFComp entries is HTML, meant to run in most any modern web browser. Just locate and open the game’s .html file, and your browser of choice should take it from there. (If the game is made of many HTML files, look for one named index.html, unless a README file in that game’s folder directs you otherwise.)
In most cases, you can play a web-based entry during the competition by tapping its "Play Online" button, too.
You will probably need JavaScript enabled in your browser to let games work properly. (If you aren’t sure whether or not you have JavaScript enabled, then you probably do; it’s almost always on by default.)
Some web-based games work completely offline, with everything you need to play in their respective download directories, but others are hosted online and require an internet connection to play.
File extensions: .gam, .t3
TADS is another popular system for creating parser IF. As with Inform, it offers its own variety of free, cross-platform interpreters you can use to load and play games created with it.
We strongly recommend using a TADS-specific interpeter to play IFComp entries created with TADS, rather than a more general multi-format IF interpreter. They tend to be much more capable at properly loading and displaying all types of TADS-based work, including those using the newer "HTML TADS" format.
As TADS games are also usually parser-based, the above links and advice regarding parser-play also apply here.
File extension: .quest
Quest is another popular IF system, albeit one whose downloadable titles work only on Windows. You can download its interpreter for free from its website. Quest games are often (but not always) parser-based, as well.
File extension: .a3c
Alan is another system for creating parser-based IF. Like TADS and Inform, playing its games requires the use of a separate interpreter program, available for Windows, Mac, and Linux.
File extension: .hex
Hugo is another system for creating parser-based IF. Like TADS and Inform, playing its games requires the use of a separate interpreter program, available for Windows, Mac, and Linux.
File extensions: .taf, .blorb
ADRIFT is another system for creating parser-based IF. Like TADS and Inform, playing its games requires the use of a separate interpreter ("runner") program, available for Windows.
You can also play ADRIFT games on Android using the Fabularium interpreter.
Note that games made with ADRIFT can have a "blorb" file extension, just like games made with Inform, but they don't work with Lectrote, Gargoyle, or other popular IF interpreters.
(Confused? Blorb is an open file format for IF games. Of IF-creation platforms that output blorb files, Inform is far and away the most commonly used, but other platforms -- such as ADRIFT -- can use this format as well.)
File extension: .exe
Games with the file extension .exe are native Windows programs. If you’re running Windows, just run them like any other program.